Who’s writing this stuff ?

Dave graduated from the University of Washington in 2006 with a degree in environmental science. He has 42 years of experience in the “workplace”, including overseas service in the U.S. Navy in the late 1960’s.  He has worked as a mathematics instructor, an electronics technician, and an antique clock repair technician. Dave has spent the past 14 years designing, studying, building and testing slow sand water filters.

Dave T

A little older now. . . .


41 Responses to Who’s writing this stuff ?

  1. Claver Nitereka says:

    Hello Dave,

    I just came across of your excellent work , I sincerely thank you for sharing it. This is going to help lot of people in non developed countries where most of people(including my parents) , living in rural areas, are still drink contaminated river water. Diseases and death toll are very high in these areas, by example in Burundi where I originally come from.

    I have been, since this Christmas, researching on roof rainwater harvesting techniques to supply potable water and using Bio-sand techniques for filtering. Another area I am researching is the DIY solar panel in order to use it in conjunction.

    As I am new in the area , I would appreciate your mentorship to conduct this project.
    Is it possible to visit or talk to you and review your systems closely if you are close to my location. I am an aerospace engineer and live in Snohomish?

    My short term goal is to provide potable water to my parents and their neighbors by April 2014.
    The project is divided in 3 steps:
    1. Roof Rainwater catchment. Installing gutter on the roof will done in February 2014.
    2. I identified a 1000 gallon barrel for water storage.
    3. Filtering, treating rainwater to make it drinking water. This is the phase I need the help and guidance. A good news is that rural areas do not have chemicals, they do not use pesticide. Most of problems are from fecal and other waste.

    I appreciate any support that can help people.

    Thank you very much again.
    Have a nice day

    Claver Nitereka

  2. filter_guy says:

    Thank you for the input, Claver; your questions bring up some important points.

    The filters here are not being used to provide potable water; and unfortunately, we cannot recommend them as a dependable method of producing potable water. The site http://www.biosandfilter.org/biosandfilter/ is the best source of information on biological sand filters that may be used for supplying potable water in areas other than the the northwest part of the north american continent. The people who run that website, biosandfilter.org, have tested filters in other parts of the world successfully for a long time (they have already done “pilot tests”), and have far better information that we do regarding that matter.

    The filters we have here do provide water that is clean enough, and safe enough to use on a vegetable garden; and these filters do significantly improve the quality of the water that runs through them. The filters will provide water that can be used for anything but direct consumption on a regular basis. Further disinfection and filtering is still needed on the output of these filters in order to make the water potable on a regular dependable schedule of use.

  3. Cassia says:

    Thank you for doing all of this research. Saved me a whole lot of time. ( :
    I happen to live in Colorado and was curious about our water regulations because just last year Costco was selling rainwater collecting barrels. I am all about sustainable living and was wanting to use one for watering my garden. Sad to hear that it is completely illegal and highly regulated. I am curious as to why, of all places, Colorado has regulations on rain water collection. Our area depends on snow melt, reservoirs and wells for our water reserves; I don’t see how collecting rain waiter would adversely affect our environment. Just another reason why I’m heading to Wyoming!

  4. filter_guy says:

    Actually, some people can legally harvest rain water in Colorado. My humble apologies if I give the impression that rain water harvesting is illegal in Colorado for every one. It is for some people, and for others, it is ok. The link in this post goes directly to the Colorado gov’t website with an explanation there.

  5. Pablo says:

    Dear Dave,

    I would like to use the slow sand filters you described in a research project that aims to provide drinking water to small groups of people in rural areas in Argentina. However, you mentioned that you cannot recommend it as a dependable method of producing potable water.

    What does the slow sand filter you present need to be able to produce potable water?

    I am looking forward to hearing from you soon,


  6. filter_guy says:

    To determine if a small slow sand filter will provide potable water, the filter would need to be set up and a pilot test done. This means the filter would need to be set up at the location where it will be running, using the same water all the time; and then be tested by a qualified knowledgeable person in the worst of conditions and the best of conditions. Also the input water would need to be tested to determine the extent of contamination. Then the owner / operator would need to be trained on how to properly use and maintain the filter. Output can vary considerably, and it is possible for a slow sand filter to produce water that is not completely purified if it is not maintained correctly. Also contamination can come from anywhere. And anything can be in water – anything. A UV filter may be needed in some cases. Be advised that the filters we have here are not the same thing as a “Biosand filter”.

    We have 12 filters running here, and I’m not sure which one you are referring to. Four of the filters purify roof water, and 2 of them purify shallow well water. These are the ones that have been tested by EPA certified laboratories. The filters work, most of the time, at this location here in the northwestern part of Washington state, with the water sources we use here: roof water, and shallow well water. The output varies considerably depending on the condition of the input water, which also varies considerably. There is no guarantee that the filters we describe here will work to provide potable water anywhere else 100 percent of the time. Without proper testing at the place of operation, there is no way to be certain of the output purity. Also, be advised that the owner / operator of any slow sand filter is totally responsible for its operation, and totally responsible for assuring proper maintenance and testing.

  7. Wendy Woodruff says:

    I recently saw a picture on a Facebook group of Free and Equal that stats that it is banned to collect rainwater in the USA. I find their picture very misleading, as I know it isn’t banned in the entire USA, but I can’t find anywhere to see just how many states it is actually illegal to do so. Can you tell me exactly how many states it is illegal to do so?

  8. filter_guy says:

    Colorado is the only state that still makes it against the law for some people to collect rainwater, otherwise all other 49 state governments have no laws against harvesting rain water for individual homeowner’s use. Texas has a law that protects the right to harvest rainwater. There may be city or county governments that have different laws.

  9. Ersan says:

    Hi Dave. Thank you for this great blog, really informative one.

    I have an hydroponic setup and i am building a quartz sand filter.
    But i have a question if you have time.
    Do you think this filter will also keep the nutrients beside the harmful bacterias?
    If so, there will be a problem for me 🙂

    Thanks in advance.

  10. filter_guy says:

    I’d have to see the plans and the construction, and then I could only give you an educated guess about its ultimate performance. Having an approved testing lab check the output water for you after about 4 weeks of operation is the best way to check a slow sand filter’s operation.

  11. glenn johnson says:


    WI AB 737 (Failed to Pass.)

    This bill would require DSPS to promulgate rules that establish standards for the installation of graywater and rainwater systems and that authorize the use of graywater and rainwater within the building, or on the property surrounding the building, from which the graywater was generated or the rainwater was collected.

  12. Hi Dave,
    You may want to update your «Rainwater harvesting regulations state by state» page concerning Ohio and Georgia. Ohio’s Department of Health provides substantial documentation on the matter: http://www.odh.ohio.gov/en/odhprograms/eh/water/pwstypes/cisterns_hwst.aspx
    whereas Georgia has a complete guideline since 2009

  13. filter_guy says:

    Andre, thank you for the helpful comment. I have copied the links and placed them in the post about rainwater harvesting laws. I really appreciate your input!! I have also given you credit for your contribution in that post. I wish more people would contribute.
    Dave T

  14. Laura says:

    Hello, I am appreciating the detailed description of your cement cistern. We’ve installed 2 precast cisterns, and have coated one of them with Ames Blue Max. It is just not curing. Think we’ll follow your lead and remove it, my question is how did you do that? There are parts near the top of the cistern that have dried, if not cured, and it seems impossible to scrape it off. Any suggestions would be so helpful and welcome. Thanks from KY.

  15. filter_guy says:

    Sorry to hear that the blue max did not work out for you.

    We did get some of it to cure up really nicely, but did not have time to wait and see if the other coating below ground level would eventually cure; and we did not want to take the chance of having it fail with a cistern full of water! It may very well have cured if we had let it sit long enough, but we chose not to take that chance.

    In our case here, the stuff that was not cured came off with water and some vigorous scrubbing with a deck brush. I had to get into the cistern on my hands and knees and scrub for several hours. I then used a wet-vac to remove the blue goo that remained.I did end up putting about 100 gallons of water in the cistern to do this after I had scrubbed it out. The part that had cured was not completely removed. I used a wire brush in a battery powered electric drill to get off what I could; then I just painted over it with the mortar/cement/sand mixture. It appears to be holding water fairly well. There is some leakage, but none showing on the top outside 2 feet where the blue max was cured and covered with cement on the inside. Also the leakage would not be so obvious if we were using the water on a regular basis. The “leakage” is partially due to my filters having some slow leaks in the piping to and from them and the cistern. Also some evaporation is happening here. It gets very dry here in the summer, and this summer was no exception. We have gone weeks with no rain.

  16. Celismar says:

    Hello good morning,

    My name is Celismar Oliveira, I am student of Agronomy at the Federal University of Lavras (www.ufla.br) in Brazil. And now we have gone through several water crises in my university for example has entertained the possibility of break in classes due to lack of water. And when I was doing research on adsorbent capacity of activated carbon was when by coincidence I came across your project sand filters. Particularly found it very interesting and can be affordable to many low-income people.
    Well, my interest is in design in Auto CAD, because I was weighing in using your model, but with some adjustments, such as using a type of activated carbon that we can get from cane sugar and ultra violet lamps to be used in the first process. Well, but that’s just flat. If you could count on your cooperation would be great if you have the design in Auto CAD’ll thank me if you can provide. Already I want to congratulate for the design and creativity, I believe it is the stock so that the world needs.
    I’m disposal for more information.

    Celismar Oliveira
    Estudante de agronomia da Universidade Federal de Lavras
    Estagiário no Laboratório de cultura de Tecidos
    Departamento de Fisiologia Vegetal

  17. filter_guy says:

    Hello Celismar, thank you for taking the time to comment with relevant information. I am sorry to say that I do not have an Auto CAD copy of any of the filters. I have only jpg’s and gif’s. What you are saying about ultra-violet light and carbon filtering media makes complete sense. The carbon filtering we have done here consists of potable water approved carbon granules in an external container. That carbon filter takes out lots of the odor, and the color in the output water. We have not used ultra violet filters here. I am sure they would work, as the water from the filters is very clear.

  18. Glenn B. says:

    Outstanding collection of laws/regulations. I can easily imagine how hard it is to dig those up and keep them up to date. Thanks for putting your the time into it. I’m looking into a roof collection system for a house that’s on a hilltop in central TN. Looking forward to learning more from your website.

  19. CarlG says:

    Hi Dave, and thanks for doing all this work. I am contemplating relocation from Arizona to the Pacific Northwest. Do you have any info or sources I might check out to ascertain various states’ regs regarding capturing rain from other than rooftops on one’s property? I am interested in permaculture: creating berms, swales, and ponds to reduce runoff, encourage flora and fauna, and increase crop and livestock potential. Thanks for your consideration. Carl

  20. filter_guy says:

    Thank you for the interest, Carl.
    When you say the Pacific Northwest do you mean the U.S., or Canada ? British Columbia is part of the “Pacific Northwest, I believe. If you are thinking about Washington state, try this link to the department of ecology:
    You’ll have to read through the links they have there.

    If you have never lived here in the Puget sound region, know that it is very, very different from places like Nevada, Arizona, New Mexico, Colorado, or Utah. It is wet here most of the time, and there is lots and lots of water. It comes at a price, though. It is dark, and skies are grey for most of the winter and sometimes for most of the summer also. Be prepared for that. Also it gets really really dark here in the winter. Right now its 2:30 in the afternoon On Jan. 5, 2015. It will be dark in about 40 minutes, and it did not get light until 8:00 in the morning. So, if you can put up with that for 5 months of the year you’ll be ok. That dark grey weather is one reason why we drink lots of coffee here. Also know that it can get very hot and dry here in the summer often in the 90’s for a week or two, and water can become an issue. Having five or six hundred gallons of filtered roof water stored for the summer is a really good idea. When you get used to the climate here, 90 degrees is really really hot.

    In most parts of the pacific northwest part of Washington state there is so much rain in the fall, winter and spring, that the average home owner has access to way more water than they will ever need for free and well within the law. Surface water runoff coming from roof surfaces is actually a problem in cities like Seattle, where roof water harvesting actually is encouraged because it helps to prevent excessive runoff in heavy rain months. There are housing developments where there are home-owners associations that may prohibit rain water harvesting, or any use of water that they collectively do not like. Be aware of that.

    Water law is super complex and different in every state. I discovered that last year doing the research for the page on this blog:

    Most of the research I did includes links to the pages at the state government sites where there is info about surface water in addition to roof water harvesting. In some states surface water and roof water are considered the same and are under the same laws and regulations. Its when the water runs into an established stream, lake, pond, or year round wetland that things get really complicated.

    Dave T

  21. chrissy2026 says:

    I found some updated information regarding collecting rainwater in Missouri. I hope this helps.

    Nice link. Thank you, Chrissy!

  22. Larry R. says:

    Just thought this would be of interest to you about the collection of rain water in Tennessee.

    (filter_guy suggests)try this link:

  23. robb says:

    Hello Dave,
    Robb here in Sammamish, WA and I have the dreaded composite roof. I have nine 50 gallon rain barrels and want to use them up for my vegetable garden. I’ve been doing the hardscape and raised bed construction. Can you suggest a web site that has the blue print for the slow sand filter? It can rain a lot here and I’m not sure how the slow sand filter keeps up with the downspout water flow. Thanks so much in advance. Please do email directly if possible. Thanks so much, robb

  24. filter_guy says:

    Sent you an email today, Robb.

  25. Sugarbean1966 says:

    Hi Dave,
    This is the California link for San Diego County in regards to the rainwater collection. The current link doesn’t take you to the correct location. thank you for your time and attention to providing this information regarding rain and filtration.

  26. Andrew Scott says:

    Hello Dave,
    I was searching online for more information regarding rainwater harvesting laws, and I noticed that you have a page that lists the laws for each state. I just thought I’d let you know that in PA, my business installs rainwater barrels that can be used to provide extra water to ponds, waterfalls and other water features that people keep in their yards. This page contains some additional information about it, but I think it’s a pretty good resource for information about how rainwater can be used in lawn and garden maintenance in PA, in case you want to link it:
    Rainwater Harvesting
    Feel free to use this page as a resource for your readers. Thanks for the information on your site, especially the information about New Jersey’s laws.

  27. filter_guy says:

    Hello Andrew. Thank you for your input, and the link!

  28. Mark Jensen says:

    Thank you so much for this exhaustive research into the legality of rain water harvesting. It is a complex issue and it’s so nice to have this resource. Kudos to you.

  29. Davin Paul says:

    Ok now I’m getting frustrated! Haha Very sorry about all these comments. I just wanted to correct it so you didn’t have to fix anything. Will give it one more try:

    Here is the corrected comment:

    Hey Dave! Thanks for publishing your research on rainwater harvesting laws. I’m putting together my own rain barrel page and your information has been an excellent resource.

    I’m curious of changes in Illinois since you last updated your site and if you would have a more positive outlook on the state presently. I live in IL, and found an exhaustive amount of rain barrel programs including the Metropolitan Water Reclamation District of Greater Chicago that has free rain barrels. They work with a majority of surrounding suburbs.

    If you want to see what I’ve found so far, click on Illinois in the “State & Local Rain Barrel Programs, Incentives & Resources” section.

  30. filter_guy says:

    Thank you for the input, Davin. I’ll look into the Illinois situation again as soon as I get some spare time.

  31. Alex Leyton says:

    I’ve been on your website a few times and have been mulling the feasibility of these filters. As I understand them, these slow sand filters naturally grow beneficial micro-organisms that devour things that are toxic to humans. The micro-organisms themselves are not harmful to humans and are kept from entering the drinking water by their inability to thrive in the gravel. You cannot use flouridated tap water to start these systems because they kill the beneficial bacteria so you need to start these filters with filtered water. Please correct me if I haven’t understood the basic operation. The two strong negative I see in these filters are:
    1. The poor flow rate.
    2. The need for constant flow.
    I’m in NYC, where annual rain fall is pretty good but perhaps not good enough to keep one of these going with natural rainfall till they are ready to deploy. Are you aware of anyone in my area who I can consult that has successfully got one running?

  32. filter_guy says:

    In response to Alex Leyton’s comment on May 12, 2016:

    I’m not aware of anyone in your area who has a functioning slow sand filter.

    You mention fluoridation of water. That process is to help prevent the
    breakdown of tooth enamel due to the acids produced by bacteria. You may
    be thinking of chlorination of water, which is to kill pathogens. I do not
    know if fluoridated water will harm a slow sand filter. Chlorinated water
    will harm a slow sand filter.

    You want to use raw water to start a slow sand filter, not “filtered” water;
    however, if your raw water is turbid, you may need pre-filtering which
    does not remove bacteria. You want the bacteria to be in the water that is
    to be run through the slow sand filter.

    Slow flow rate can be a problem. Also the fact that water must run through
    the filter constantly is an issue. The filter contains living organisms
    that need oxygen and food.

    A recirculation pump can keep a small amount of water flowing through one
    of these filters continuously. A small solar panel can run a small pump
    that recirculates water during the summer when rain is not falling. We use
    recirculation here and it has worked for 8 years. Here is a link to one of
    the recirculation systems we use here:


  33. Jennifer Dale says:


    I think it may be illegal some how in FL because I’ve heard of several people getting in trouble like this above woman

  34. filter_guy says:

    Thank you for the link in your comment below, Jennifer. It is very important to keep informed about this kind of situation. I see the article is two and a half years old. Do you have any information on the current status of this issue as it relates to Robin Speronis? What I can find indicates she is still being harassed by the local city government. I’ve found no indication that the Florida state government is involved in this. In fact the Florida state government encourages rain water harvesting:

    There may be additional issues that have not been mentioned in this case. Ms. Speronis has apparently had solar power installed in addition to using rain water. Utility companies don’t want solar power to cut in to their profits. There may be (exaggerated and perhaps untrue) property value issues, or worries about mosquitoes in the rain barrels. None of this even comes close to justifying the harassment Ms. Speronis has reportedly been experiencing.

  35. Divergent_Fan_Lover says:

    Thank you for all the hard work you put into this site. I am using this as a major resource, and if this book I am writing ever gets published, rest assured this site will be in my resources section. Thank you in advance.

  36. Major Payne says:

    Dave, Great website. I have my slow sand filter constructed. It has two roughing compartments before prior to the sand filter. I am having a hard time finding sand that is .15-.35mm with a UC of 2 of less. My property is in OK and I live in TX. The closest place I can find the sand media is in FT Smith AR. They have a sand they call “minus,” with a size of .27-.30mm and a UC of 1.79. Where do you get your sand media? Comments? Help?

  37. filter_guy says:

    Major Payne asked about sand:

    Two posts on this blog describe how to acquire sand:

    this post describes how to sift your own sand:

    This post give more info about sand:

  38. Christopher Hisgen says:

    Nevada law changed drastically recently.
    I can send you the revision once I have your email address.


  39. Ashley B says:

    Hello, im a college student who is currently doing a project with our theme being water. I decided to talk about the collection of rainwater and happen to cross upon this article. Part of the assignment is to have a primary source so i wanted to know if it was okay to do a small quick interview? it would be greatly appreciated.

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