Category Archives: slow sand water filter study and construction

We have had a number of questions, over the past 5 years, about drinking the water from the slow sand filters described on this blog and on the websites associated with this blog. I’ve responded periodically to each comment, but … Continue reading →

We were recently contacted by a local water district representative regarding setting up some slow sand filters for schools’ irrigation water supply. They wanted a “green” “sustainable” technology to filter water from their rainwater / roofwater harvesting system. In speaking … Continue reading →

Filter 5, the newest addition to the project, has been filtering water since the last major below freezing weather event (about 6 weeks) using only gravity feed, and manual re-circulation using a 5 gallon container. No electrical power or pumps … Continue reading →

Update; January 17, 2022: As of 2017, rainwater harvesting is legal in Nevada. There are regulations, however. And the use is limited, but it is no longer illegal to harvest rainwater in Nevada. https://water-law.com/can-nevada-gardeners-collect-rainwater/ Update; September 16, 2016:   We have … Continue reading →

Above are the tests on filter 4 after 3 weeks of running, following being frozen solid for the month of January, 2013. The filter has not had enough water running through it to completely restore the active bio-layer. The roof … Continue reading →

A few notes here about backwashing  a small slow sand filter. This mainly applies to DIY (Do It Yourself) filters, with one exception noted below in the next paragraph.  Do not forcefully backwash your DIY slow sand filter. You may very well … Continue reading →

The filters described on this blog and the associated websites have been tested by 2 different EPA certified laboratories: AmTest in Kirkland Washington, and The city of Everett, Washington environmental lab The test results can be found here and here. … Continue reading →

Filter 5 was frozen solid and not running for 2 weeks in January of this year (2013). Before that for 5 days the filter froze at night, and then ran for 6 hours each day. As of Jan 25 the … Continue reading →

All but two of the filters have been frozen solid for 2 weeks (15 days), with the exception of the two filters that purify shallow well water. The water that runs through them has been running continuously and was still … Continue reading →

The filters we work on here in western Washington state have been in operation outdoors through temperatures as low as 15 degrees F (at night) for as long as 1 week, with below freezing (32 degrees F) continuously for 7 … Continue reading →