Introduction
The slow sand filter projects documented on this website have taken place in the pacific northwest area of Washington state, USA. The first filter project (filter one) was started in early 2007. All of the projects are ongoing and will continue as long as the author is able. The water quality tests that have been done by epa certified testing laboratories are noted as such. The preliminary field tests are done onsite and are also noted as such. The researcher has a four year degree from the University of Washington (class of 2006) in environmental studies plus 35 years of experience in non-academic work. Chemicals used for drinking water treatment such as chlorine, or ozone that produce toxic cancer causing byproducts are not used in these filters. The longest running slow sand water filter project this site documents has been ongoing for ten years (it was started in the summer of 2007). It will continue as long as possible.

Keep in mind that "Backwashing" a biological sand filter will destroy it.; and that a biological sand filter is constantly full of water up to and covering the top surface of the sand inside by at least 1 inch or more - the sand must not be exposed to air.
Know that the content of this site will change considerably as this study continues.

Rain barrels are now legal in Washington state! For over 90 years it has been illegal to catch rainwater in Washington state.^{note 2} As of October 9 2009, catching roof water is no longer a crime! The department of Ecology in Washington state (the D.O.E.) has finally clarified the law so as to allow individuals to catch rainwater for their own use. (from this preceding link, click on the links at the D.O.E. site on the upper right hand side of their page that say "new" highlighted in yellow.)

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So far work has been done on Five separate small slow sand filters:

-10-18

Filter one (external link)	Filter two   float valve installed 2011-04-07
Filter three
filter 4	filter 5