Rain water harvesting and slow sand water filters

First of all, look to the table of contents page on this blog to get detailed info (from links to sources) on rain water harvesting laws, or lack of them,  in the U.S. .  These laws are changing rapidly and becoming more and more permissive regarding rain water harvesting.

Update June 9, 2014: All 50 state government websites and/or associated websites have been checked. The only state where it is against the law (for some people) to collect rain water is Colorado, its legal in all other states. Know that some counties and cities may have laws that differ from their state government laws.

Update December 15, 2013: The number of state government sites checked is now up to 24. Still no laws found against rain water harvesting by individual homeowners.

Update: August 21, 2013: So far I have looked up regulations on 18 states in the U.S. :  Maine, Tennessee, Georgia, Washington state, Oregon, Utah, Idaho, Missouri, South Dakota, Illinois, Wisconsin, Kansas, Arkansas, New Mexico, Colorado, South Carolina, and New Jersey

I have found absolutely nothing specifically prohibiting rain water harvesting by individuals in all cases. There are regulations on industrial pollution, new construction, and large amounts of water diversion –  typically over 100,000 gallons. There are, also, hundreds of counties, cities, and residential districts that may indeed have laws against rain water harvesting by individuals, but not at the state government level.

Directly below is a document endorsed by the mayor of Albuquerque, New Mexico regarding  rainwater harvesting:

http://www.ose.state.nm.us/water-info/conservation/Albq-brochures/rainwater-harvesting.pdf

Here is one regarding state sponsored rain water harvesting in the U.S. state of New Mexico:

http://www.ose.state.nm.us/water-info/conservation/rainwater-harvesting.pdf

Here is another link to a story about rainwater harvesting becoming legal in Colorado:

http://www.nytimes.com/2009/06/29/us/29rain.html?_r=0

and from the above story, here is an update to one of the links they had that was changed: (we found the study they speak of that shows the inaccuracy of the assumptions used to form the original restrictive Colorado laws regarding rainwater harvesting). This link goes directly to the PDF file that contains the study “Holistic Approach to Sustainable Water Management in Northwest Douglas County” the part regarding rainwater recharge of ground water starts on page 25 of the report. It shows that lots of the rain in Colorado never actually made it to the ground water before development began. This is a complex study but it is clearly written and you must read it to understand the issues:

http://www.westernresourceadvocates.org/water/pdf/Rice–HolisticApproachtoSustainableWaterManagementinNorthwestDouglasCounty.pdf

Lots of “prepper” blogs refer to the “southwestern states” as having and creating laws that make it “against he law” to harvest rainwater. Here is the story on the southwestern states straight from those states. If one reads this document, one will discover that the laws are not becoming more restrictive, they are actually becoming way, way less restrictive:

http://www.cap-az.com/Portals/1/PublicInformation/AwardForResearch/Gaston–Rainwater-Harvesting–May-2010–CAP.pdf

Now, links to some of the blogs I found that really screw up the information about rainwater harvesting so as to spread hate, discontent, fear, uncertainty and doubt. There are so many “prepper” blogs that have hyped – up rants about how repressive government is ripping away at the “average citizen’s rights”. Some of this may be true, but not so with rainwater harvesting. While it is imperative that big government be kept in check, we do no good by doing so with un-truths, exaggerations and prevarication of the facts.

Some disturbing misunderstandings and inaccuracies here:

http://www.reddit.com/r/todayilearned/comments/1gwwuq/til_that_harvesting_rainwater_is_illegal_in_many/

This one is not as bad as the previous, but there are posts here that show peoples ignorance:

http://message.snopes.com/showthread.php?t=85310

This one is full of mis-information:

http://beforeitsnews.com/politics/2013/04/collecting-rainwater-now-illegal-in-many-states-2513766.html

More misinformation here. This fellow has millions of gallons of water stored. If you do some research you will discover that this guy owns 170 acres of land in/near the city’s watershed, and only about 15 miles from Medford, Oregon. He has been there for, apparently, many years, and has had these ponds for many years. It is claimed that he did get approval from the government for the ponds, but then they went back on their word and came after him. It gets real hot and dry in the summer in Medford, Oregon. They need all the water they can get. He has 170 acres of land with lots of water on it. Now, the city wants his water. Again, follow the money trail. Somewhere, someone stands to make a lot of money on water. The sad thing is that lots of people there really need water in the summer. Is it “big government” or, “big business” or both that are at the source of this issue? Let’s look at this from this guy’s perspective (assuming he is telling the truth).  He buys land, or inherits it from his kinfolk. He is miles from urban sprawl, and has no desire to harm anyone else (we assume). It is obvious that the nearest neighbors have all the water they will ever need. Along come land developers – the city grows exponentially. Now they need more water to serve the newly created municipalities; and even more to create more development. They want his water. They find a way to get at it through government regulations.  Sound crazy? No. This similar scenario, on a much larger scale, actually happened in California early in the 20th century with the Hetch Hetchy Reservoir dam. Read more here.

read about the issue near Medford here:

http://www.dailymail.co.uk/news/article-2187977/Man-jailed-30-days-building-reservoirs-HIS-OWN-LAND-water-20-Olympic-sized-pools.html

This is not about the average person collecting several hundred gallons of water in rain barrels; but this issue is worth watching closely. But lets know the truth. Read this stuff below in the next link for yourself – fox news really hypes it up good:
http://www.foxnews.com/leisure/2012/08/16/man-jailed-for-collecting-rainwater-in-illegal-reservoirs-on-his-property/

More fear, uncertainty, doubt, hate and discontent, and inaccurate information in this link.  At this site there are two links to stories of situations that are indeed good examples of government overstepping its authority; but these issues are not about rainwater harvesting being against the law; however they are (apparently) accurate and do represent abuse of power:

http://offgridsurvival.com/rainwaterillegal/

Some mis-information here:

http://www.permies.com/t/7164/energy/Collecting-rainwater-illegal-states

More inaccurate info here:

“There are several states where rain collection is restricted or illegal. It’s totally illegal, for example, in Oregon and Utah.”Sorry dude’s, but you’re totally wrong. Check the other links on this blog you are reading. Utah just lifted some restrictions on rainwater harvesting, and Oregon only regulates some types of rainwater harvesting.

http://www.raincontrolaluminuminc.com/is-collecting-rain-water-illegal-in-florida/

More fear, uncertanty and doubt here:

http://www.buyandhold.com/bh/en/education/mom/linda/2010/mom410.html

I could go on finding links for hours. They are all over the net. The only upside to all this inaccurate hype, is that people may be made aware that there are potentially others who will want to control their access to water, but be careful, always, ALWAYS, follow the money trail. Government officials can be influenced by money from wealthy corporations. This is the real threat to our “freedom”. And if you are led to a conclusion by deliberate un-truths, exaggeration, and mis-information, does the end really justify the means; and how would you feel when you found out that all the info you got to justify your stance was basically bs?  Duped? Lied to? Go figure.

If anyone has information showing that the stuff I post here is wrong, or inaccurate, please post your reply here with a link to the source, and we’ll change this post to reflect the new information.

If you post your opinion (a statement with no link to the source) your post will be marked as such and we will change nothing. You are entited to your opinion. Spamdexing and deliberate attempts at free advertising will be deleted immediately.

Update July 15, 2013:

New Jersey regulations do not appear to make rain barrels, or rain water harvesting for the individual home owner against the law. There are programs in the state that encourage rooftop rainwater harvesting:

The official website of the state of New Jersey regarding water:

http://www.state.nj.us/nj/green/water/

At the above page click on the link that says “all about water”

http://www.nj.gov/dep/watersupply/

Then click on the link that says “Water allocation and registrations”

that takes you here: New Jersey state website about water rules:

State of New Jersey Department of Environmental Protection Division of Water Supply and Geoscience

http://www.nj.gov/dep/watersupply/g_reg.html

New Jersey water supply allocation rules 2008:

http://www.nj.gov/dep/rules/rules/njac7_19.pdf

The PDF at the above link is 90 pages. The definitions section clearly states: nothing about rain water harvesting for or against. Also the water “owned” by the state is clearly defined as not including rain, but just about everything else.

Rutgers (in N.J.) paper on rain water harvesting:

http://njaes.rutgers.edu/pubs/publication.asp?pid=FS1162

at the page the above link takes you to click on the “download pdf” button

This should offer you the down load of:

“Rooftop Rainwater Harvesting For Plant Irrigation I:Design

Concepts and Water QuantityFact Sheet FS1162

Cooperative ExtensionSalvatore S. Mangiafico, Environmental and Resource Management AgentChristopher C. Obropta, Extension Specialist in Water ResourcesElaine Rossi-Griffin, Program Coordinator, Environmental Science”

from Page 4:

“Legal ConsiderationsThe authors know of no regulations at this timegoverning cistern installation for private use in NewJersey except that using cisterns in a drinking watersystem is typically not allowed (NJDEP 2004). Otherstates may have regulations stipulating, for example,the allowable size and material of storage tanks, orthe maximum allowable amount of water that can beharvested. State laws and local ordinances should beconsulted when designing any rainwater harvestingsystem.”

Update June 26, 2013:

Illinois: Rainwater harvesting is highly regulated and the “regulations” are incredibly complex. That said, the codes there have recently been changed to allow, what appears to be “rain barrels”. Here is a quote from the regulations:

“Section 890.2105 Permits  Where permits are required by the authority having jurisdiction, it shall be unlawful for any person to construct, install, alter, or cause to be constructed, installed, or altered any alternate water source system in a building or on a premise without first obtaining a permit from the authority having jurisdiction.A plumbing permit is not required for the following: ILLINOIS REGISTER DEPARTMENT OF PUBLIC HEALTH  NOTICE OF PROPOSED AMENDMENTS a) Exterior rainwater catchment systems used for outdoor drip and subsurface irrigation with a maximum storage capacity of 360 gallons.b) Rainwater catchment systems for single family dwellings where all outlets,piping, and system components are located on the exterior of the building. This does not exempt the need for permits if required for electrical connections, tank supports, or enclosures.”

If someone says “rainwater harvesting in Illinois is against the law”, they are partially correct. . .  however, in reference to rain barrels, they are wrong. This is why I have given Illinois, a near failing grade on rainwater harvesting. Way ,way, wwwaaaayyyy too many regulations. Here is the URL of the pdf document I accessed on June 26, 2013 at 0930 PDT:

http://www.pcaofchicago.com/Docs/Documents/Part_%20890_Plumbing_Code_Amendments_4_10_13.pdf this is from section 890.2105 which turns out to be page 137 on a “fit page width” pdf reader.

Update June 19, 2013:

A recent search that found this blog was asking why it is against the law to capture rainwater in Kansas. The following link to the Kansas gov’t site shows clearly that it is not against the law for people to capture rainwater in Kansas for their own personal use; even lots of it for a small farm is ok to catch. At the page the link takes you to, go all the way down the page to where the “Rainwater harvesting Q&A” section is located. There you will read the info straight from the source. If you read it carefully, you will find that the Kansas government has the foresight to require more than 15 acre-feet per year to be regulated. This makes total sense, but can easily be misconstrued to mean that nobody can collect rain water. This is a good example of how facts get distorted by mis-information and those who wish to spread fear, uncertainty and doubt. What the regulations are actually saying is that a person can’t “hog” all the water.  Like making their own personal lake. The gov’t is actually trying to keep big businesses from taking water from the citizenry; this is NOT about the gov’t trying to take water away from the citizenry. . . .   it is still a good idea to keep a close watch on government, and a closer eye on corruption and the money trail. Closer reading of the document, suggests that individual cities in Kansas may have ordinances regarding rain water harvesting that are in addition to the state’s laws.

Update: June 21, 2013

Another search about the legality of harvesting rain water found this blog; this time regarding the state of Wisconsin

We found 2 pages with info at the Wisconson DNR site.

http://dnr.wi.gov/topic/WaterUse/documents/PermittingFactsheet.pdf

At the above link is the explanation of what they mean by “withdrawal”  below is the info in quotes:

“What is a withdrawal? What does it mean to withdraw?Withdraw or withdrawal means the taking of water from surface water or groundwater.There are many different methods for withdrawing water including wells, intake pipes,and ditches. When someone withdraws water, it is taken out of or redirected from its natural course making it unavailable for other purposes,even if only temporarily”

The next link is to info that specifies when a permit is needed:

http://dnr.wi.gov/topic/WaterUse/permits.html

“Water use permitting Background Effective December 8, 2011, a Water Use permit is required before persons may withdraw water in quantities that average 100,000 gallons per day (equivalent to 70 gallons per minute for 24 hours straight) or more in any 30-day period from groundwater or surface water in the Great Lakes Basin [PDF 764KB]. Examples include public water systems, high capacity well owners, and others who withdraw water from lakes and streams such as fish farms and golf courses.There are two types of Water Use permits:Water Use General Permit – Required for withdrawals that average 100,000 gallons per day or more in any 30-day period but do not equal at least 1,000,000 gallons per day for 30 consecutive days.Water Use Individual Permit – Required for withdrawals that equal at least 1,000,000 gallons per day for 30 consecutive days.”

It is hardly concievable that a rain barrel setup at the average homeowner’s residence will use more than 100,000 gallons in a month.

My interpretation is : its not against the law to set up rain barrels in Wisconsin.

What’s yours? Does anyone from Wisconsin have any more info?

As I continue to read through regulations on this issue, a pattern is emerging:

1. Most state governments desire to protect citizen’s right to access clean safe water.

2. Wealthy people who desire to either hoard, or hog water for their own “profit” are the ones who scream the loudest and spew forth prevaricated, biased information; when state governments tell them they cannot, blatantly, obviously, and deliberately prevent others’ access to water.

3. Regulations on rain water harvesting are changing rapidly. Washington state, Utah, and Colorado have recently changed their laws on rain water harvesting to allow individuals the freedom to set up rainwater catchment systems without requiring permits.

4. Government is NOT getting “more restrictive” regarding rain water harvesting, quite the opposite, restrictions are being removed rapidly.

5. Cities and counties often have restrictions that state governments do not have, and don’t control. This may be where some of the negative attitudes are coming from that are so prevalent on some “prepper” blogs and websites.

6. We the people are the government.  If you must point a finger, be sure there aren’t 3 more pointing right back at you on your own hand !!!!!

Again, if anyone reading this has any information that adds to or contradicts anything on this blog, post it here with a link to the source, please.

After the failure of filter 5 in late May of this year, we changed the top 6 inches of sand from .15 mm effective size, to .25 mm effective size sand. We are now using a re-circulation system on this filter.

So far, there has been a gradual improvement in the clarity of the water. The foul odor has also gone.

More later. . .   .

Following the failure of filter 4, in early June, 2013 the following modifications were made on June 5, 2013 when the filter was restarted:

The top 3 inches of sand was removed and changed from .25mm effective size to .35 mm effective size. The inside of the barrel was scored horizontally using #60 grit sandpaper. This was done around the entire inside surface in a 3.5 inch wide band at the top layer where the .35 mm sand sits on top of the .45mm sand.

The sand used on the top is #30 Unimin industrial quartz processed using a 30 mesh stainless steel screen. The sifted sand used consists of the 60 percent retained by weight on top of the 30 mesh screen. The 30 mesh screen is square weave stainless steel; .012″ wire size, and .0213″ opening (.54mm). Supplier is McNichols. The part number of the wire screen is: 3830123610.

The flow rate at initial set up was .203 cubic meters per hour. This works out to an output of 55 litres per hour.

30 gallons of clean filtered water was run through the filter to clean it out.

This is a summary in outline form of the last four posts:

Critical considerations when setting up a small slow sand water filter:
A. Sand size
.35 mm effective size is the best overall choice

B. Input water turbidity
Turbidity levels below 5 NTU are best.

C. Constant water flow must be available
Water must flow through a biological sand filter (slow sand filter) constantly.
They cannot be allowed to sit idle, and the water must come from the same
source all the time. Some sort of recirculation of already filtered water must
be provided during dry spells when rainwater is being filtered

D. Container must not be smooth on the inside
The inside of a plastic container must be rough and not smooth. #60 grit
sandpaper can be used to score the inside of the container horizontally.
If the inside is smooth, contaminated water will slip down the sides
between the sand and the plastic.

E. A first flow diverter may be necessary
A first flow diverter (often callled a first flush diverter) must be used in
most cases, unless the roof surface is completely in the open and there
is minimum air pollution surrounding the area.

F. Stop output flow when wet-harrowing
When wet harrowing the filter, the output must be completely shut off
before the procedure starts.

G. Pre-filtering of roof water runoff is absolutely necessary in most situations
Some sort of prefiltering of roof water is necessary, such as a first flow
diverter, a roughting filter, screens on the gutters, or inserted into the
downspouts.

If the above recommendations are not followed, failure is highly likely.

I’ve had another comment on the YouTube video we posted regarding the first flow diverter with a float seal device. The comment is as follows:

“I was wondering the same thing, there’s usually two bung holes, why not use them. Also, I don’t see the need for the vent, doesn’t air escape out the inlet? And why not use a smaller barrel if you’re gonna put a “reset” faucet in 1/2 down a 55 gallon barrel. Seems like if you use a 30 gallon barrel your “reset” and clean out faucet can be one and the same, at the bottom.”

As far as the vent issue; yes, the water will “flow” without a vent, but it will not be dependable, and will plug up constantly and become a real problem, I’ve been there and done that. I’ll explain in detail below.

I’m not an engineer, so I can’t give a complete technically correct explanation of why a vent is needed; however I can give an accurate explanation of what I observed, over and over again. If there is no vent, the diverter will overflow during a heavy rain event, and the slow drain will not be dependably adjustable. I built the first diverter without a vent and it did not work until I put a vent in it. It would act as if it was full when it was not (water would spill out over the top before the barrel was full), and the slow drain would not work. Then, I put a vent in the top of the barrel, and everything worked.

Now, possible explanations:

The input pipe is too small preventing air from escaping when water would flow in fast; or there was debris blocking the input. It is a fact that water will displace air when it flows into a sealed container. Also, if there is a float seal inside the input pipe, there may not be enough air flow past the seal to allow enough water to drain out slowly and still make room for enough air inflo to allow water to escape from the barrel.  This is because the float is a 3 dimensioal object and has a diameter. Water surrounds it completely and the forces it up against the beveled inside surface of the pipe. In a 55 gallon barrel, this amounts to a cylinder of water that is 1.5 inches high minimum if a ping pong ball is used as the float seal ( assuming the barrel has a perfectly flat top which most do not – they are curved upwards on the inside. That works out to 2 and a half gallons of water pushing up on the float device. That means the slow drip has to let out over 2 gallons of water with no where for air to enter as the water drains. It won’t work. The slow drain plugs up. A similar situation happens if just a y is used. The water backs up to the y output pipe so there is still air flow problems inside the barrel because of the water above the opening in the barrel.

This is the second comment regarding the barrel size, and using the pre-existing threaded holes on barrel.

Let me elaborate and explain. The diverter I show is by no means the “only” way to build a rainwater diverter, and all the suggestions are appreciated. I did not explain enough of the “whys” in the video, just the “hows”.

Neither one of the pre-existing threaded holes were used because the positioning of the barrel required the hole to be in the center. This diverter we built did use one of the pre-existing holes.

The vent is a must, particularly if a float seal is used. If the diverter is to work without problems, it must be airtight except for the vent; otherwise it leaks wherever there is an opening. The float seal “seals off the input” this effectively seals the barrel airtight, and keeps fresh runoff from mixing with the more toxic first flow water. Once the barrel fills, the slow drip drain will not work correctly; it will “drain” but will difficult to adjust. I’ve already tried adjusting the slow drain without a vent in the barrel. It is not consistent enough to be dependable.  If the barrel is not air tight the float seal will not work. So, the barrel must be airtight, and there must be a vent. In a very heavy rainfall, flow into the input will be unacceptably low, if there is not a vent, because there is no where for the air inside the barrel to go except out through the same place the water enters. The vent is necessary, but it does not have to look like the one I have. If anyone has built a diverter without a vent, perhaps they will post a link to the video here. This would be most helpful to others building their own diverters.

Yes a smaller barrel would work, if you can find one, that is. We used what was available, inexpensive and reusable. Also, having some of the unfiltered water from the roof is necessary here in the summer. We often get 3 or 4 weeks without any significant rainfall and water must run through the slow sand filters we feed from the diverters. The unfiltered water from the lower part of the diverter is used by mixing it with recirculated water in small amounts ( 1 cup of unfiltered water to 5 gallons of filtered water) This supplies food for the schmutzdecke, as we recirculate water through the filters during dry months. If you’re not using a slow sand filter, then you probably don’t need that extra water; it will just go stagnant any way, so a small container might be a better choice. Keep in mind that the amount of “diversion” you need is totally dependent on the roof size, and the surroundings. Here, in the forest, we have huge amounts of nasty stuff on the roof and need at least 15 gallons of diversion per 100 per square feet of roof surface directly under trees. We have huge trees, and lots of critters – they really mess up the roof surface. See the trees in the image below.

lots of trees around the location. Most of these trees are over 100 feet tall. The house is in the center of the image.

Update, May 30 2013:

Several issues have been brought out by the situation in the previous post regarding filter 5, which is set up to filter roofwater. Roofwater can vary considerably depending on the physical, and geographical location. Temperature, acid rain, debris, animal and bird droppings, pollen, and dust will greatly influence the water quality.

1. If the input water will periodically increase in turbidity, the sand size must not be smaller than .25 mm effective size. If the input water is consistently very non-turbid, being less than 2 or 3 NTU, then .15 mm effective size may be ok.  A value of .35 mm effective size for all the sand in the filter is the best overall choice if the input water is subject to drastic changes in turbidity at times. Fine grained sand will clog up very quickly if the input water becomes more turbid (cloudy – containing microscopic particles of dust, pollen, or bits of debris from roofing material), and this creates the need to clean the top sand layer often, resulting in very poor performance and increased opportunity for anaerobic conditions to start up in the filter.

2. Most importantly (this is extremely important), re-circulation of filtered water through the slow sand filter is absolutely necessary, if rainwater/roofwater is to be filtered. These filters cannot be allowed to sit idle with no flow. The filters here that malfunctioned and became anaerobic did not have automatic re-circulation of filtered water; and I neglected to add filtered water daily. The water I was adding to filter 5 was from an open bucket which had become contaminated, and I was not adding water often enough. Furthermore, the water I was adding did compound the problem because of the high turbidity level of input water due to the diverter malfunctioning combined with the high turbidity level of the contaminated water from the open bucket. These filters are not foolproof.

The most recent slow sand filter set up here (filter 5) has failed miserably. I’ve done everything right – or so I thought. There is a diverter in the line that supplies (supposedly) water with very low turbidity to the input of the filter. I’ve tested the output water and found it to be quite free of coliform, and ecoli bacteria. I’ve used the same design as the other filters here. I’m still checking this out, but for now it looks like the main reasons for failure are my own mistakes being specifically, lack of proper maintenance, and failing to be aware of obvious major changes in the surrounding area.

This filter had been working quite well; up until about 4 weeks ago – several weeks after we had the large fir tree right above it trimmed. The tree has shed needles and they became trapped in the gutter. Then, we had some very warm sunny weather, and this gave all that junk in the gutter time to decompose slightly with plenty of anaerobic action.  Then the weather turned cool, and the rains returned with a vengeance. The rotting organic material built up there and then flowed into the diverter, plugging it up and causing very turbid contaminated water to flow into the filter.  I thought the filter should be able to handle that. Wrong, very very wrong. The filter quickly plugged up and the flow was, for all intents and purposes, completely stopped. I tried a wet-harrow cleaning. It did not work, and the output became horrifically foul. I had to remove the top 3 inches of sand and replace it, and drain off all the water on top, which was filled with very nasty stuff. This is a complete failure. It is a good thing we were NOT using this filter to supply drinking water.

Why did this happen? I still do not have all the answers, but I can tell you the mistakes I made (mostly breaking my own rules I rant about all the time):

1. I did not monitor the diverter. The slow drip plugged up and the diverter stopped working, spewing excessive decomposed organic material directly into the filter.  The diverter design needs modifications for working in a highly contaminated environment.

2. When I wet-harrowed the filter, I forgot to shut off the output, as a result nasty water flowed down into the lower sand layer.

3. I did not keep a close watch on the gutter after the work was done on the tree above it. I should have known there would be issues with lots of debris falling from the tree’s branches.

4. The top layer of sand is .15 mm effective size. That is too fine for the location. It should be .25 mm at the smallest. Also, a roughing filter should be used in this location because of the excessive amounts of debris in the area.

5. I wrongly assumed that what worked well 200 feet away, would work right under the tree, too. (This is a huge tree – huge: 4 feet in diameter at waist height, and over 125 feet tall) There is lots of stuff in that tree. I failed to take that issue into consideration.

These filters work, and they work well – but they do have limitations; and each situation is different. Be sure to check out a potential location carefully. Do a “pilot test” for 1 year if possible, to determine the operating situation. When wet harrowing one of these filters, be sure to completely shut off the output flow until finished with the wet-harrowing, and the water on top of the sand is clear.

This all does not mean that slow sand water filters are not good. This post, and this entire blog is here for the purpose of learning. So far, these filters have worked well, if properly maintained and understood. All the other filters here are working without fail. It does look as though this failure is due to my own negligence. . .   but there may be other reasons?

Update; October 5, 2013:

After 5 months of testing and observing this filter, and filter 4 which also failed; it has been determined that maintaining a constant, consistent flow of water through the filter is the single most important aspect of operation. The failure to do this was the main reason for the failure.

More info is coming as I investigate this mess. If anyone has suggestions, please do post them here in the comments section.