Slow sand filter field test (filter 5)

Filter 5, the most recent filter set up here in May of this year is now working.  The drainpipes inside the filter at the bottom of the barrel are covered by 4 inches of pea gravel. The sand directly on top of the pea gravel,  on the bottom, is .25 mm effective size with a U.C. of less than 2; and  700 lbs was used. The top sand is .15 mm effective size with a U.C. of less than 2; and 150 lbs was used. The supernatent water depth is approximately 8 inches. The white bucket on top is a 5 gallon reservoir that feeds 1/2 inch pvc drain pipes with small holes drilled in them. The drain pipes are inside the barrel at the very top just under the lid.
This filters roof water from a composition roof. The sand surface area inside at the top of the filter sand is: .2452 sq. m. .  The container depth 40 inches. The filter was started 2012-05-01.

slow sand filter image

This is a picture of filter 5, after the series of rain storms and wind storms that have passed through here Dec. 2012.

The results of the most recent field test on this filter are shown below. Please note: this is a field test and was not done by an epa certified lab. We did this test here using prepared solution from Micrology Laboratories..

The pink dots are coliform bacteria, the blue/purple dots are ecoli bacteria. “Pre-filter” means the test was done using water taken right out of the top of the filter’s supernatent water source, that is water that will be running through the filter on an ongoing basis. “Post-filter” means the test was done using water taken directly from the output pipe of the filter.

slow sand filter water tests

These are the field tests done on filter 5 as of December 21, 2012. The input and output water was tested for the presence of coliform and ecoli bacteria.


This entry was posted in slow sand water filter study and construction. Bookmark the permalink.

1 Response to Slow sand filter field test (filter 5)

  1. Julie B says:

    Bookmarking this as reference for near future use… Thank you Dave.

Leave a Reply

Your email address will not be published. Required fields are marked *

× nine = 81