Flow Tests on Slow Sand Filters 1,2,3,4 and 5 from our website slowsandfilter.org

This is a selection of information from our website. There will be more to come in the following months. This information is part of our ongoing research that started back in 2007. Fourteen years of work, so far. We will try to publish all of it in a somewhat understandable way. Understand that there are thousands of hours of work here. And much detail; very much detail.

FLOW SUMMARY FOR TESTED SUCCESSFUL DESIGNS OF SMALL SLOW SAND WATER FILTERS
See faq 31 for an explanation of flow rates
or the U.S.D.A. site has a good explanation of water flow through sand
Filter 1 (fourth configuration)*
input: roof water
using first flush diverter. 3 tab comp. roof.
top layer of sand .15mm effective size
bottom layer of sand:
non-graded. approx. .65mm effective size
electric pump recirculation at less than 1 L/hr.
container diameter: 23 inches
sand surface area .26791 sq m
container depth: 30 inches
Filter 2*
input: pond water
top layer of sand: .15mm effective size
bottom layer:
non-graded “fine” sand approx .30mm effective size
container diameter: 22 inches
sand surface area .2452 sq m
container depth: 40 inches
2010-09-16: this filter now
has a float valve installed

Filter 3 (with float valve flow control).
input: shallow well water
top layer of sand: .25mm effective size
bottom layer: 35mm effective size.
container diameter: 22 inches
sand surface area .2452 sq m
container depth: 40 inches
Date.
12 L/hr (10 cm supernatant water depth) (.045 meters/hr) no measurement no measurement 2008-01-02
3 L/hr (10 cm supernatant water depth) (.011 m/hr) 12 months continuous operation no measurement no measurement 2008-12-01
no measurement 72 L/hr (20cm supernatant water depth) (.286 meters/hr) 90 L/hr (16.5cm supernatant water depth) (.358 meters/hr) 2009-02-08
14.1 L/hr (10 cm supernatant water depth) (.053 meters/hr) 2 months running time
was totally frozen in Dec 2008 / Jan 2009.
42 L/hr (20cm supernatant water depth) (.167 meters/hr) 45 L/hr (16.5cm supernatant water depth) (.179 meters/hr) 2009-04-08
13.84 L/hr (14cm supernatant water depth) (.052 meters/hr) 40 L/hr (20cm supernatant water depth) (.159 meters/hr) 48 L/hr (18.5cm supernatant water depth) (.191 meters/hr)** 2009-04-26
13 L/hr (14cm supernatant water depth) (.049 meters/hr) 36 L/hr (20cm supernatant water depth) (.146 meters/hr) 45 L/hr (18.5cm supernatant water depth) (.183meters/hr) 2009-05-11
12 L/hr (14.5cm supernatant water depth) (.045 meters/hr) 36 L/hr (20cm supernatant water depth) (.146 meters/hr) 36 L/hr (18.5cm supernatant water depth) (.146 meters/hr) 2009-08-07
12 L/hr (14.5cm supernatant water depth) (.045 meters/hr) 36 L/hr (20cm supernatant water depth) (.146 meters/hr) 25.7 L/hr (18.5cm supernatant water depth) (.104 meters/hr) 2009-09-04
9 L/hr (14.5cm supernatant water depth) (.034 meters/hr) 22 L/hr (20 cm supernatant water depth)(.09 meters/hr)
added 48 liters of roof water from diverter output
28.8 L/hr (18.5 cm supernatant water depth) (.117 meters/hr)
added 48 liters of roof water from diverter output
2009-09-21
10.74 L/hr (14.5cm supernatant water depth) (.040 meters/hr) added 12 litres of undiverted roof water 22 L/hr (20cm supernatant water depth)(.09 meters/hr) (no significant change)
added 48 liters of roof water from diverter output
25.7 L/hr (18.5cm supernatant water depth) (.103 meters/hr)
added 48 liters of roof water from diverter output
2009-10-08
9.24 L/hr (14.5cm supernatant water depth) (.035 meters/hr) 21 L/hr (20cm supernatant water depth)(.086 meters/hr)
21.81 L/hr (18.5cm supernatant water depth) (.089 meters/hr)
2009-10-12
10.58 L/hr (14.5cm supernatant water depth) (.039 meters/hr) 20.57 L/hr (20cm supernatant water depth)(.0839 meters/hr)
source water changed to surface well
21.17 L/hr (18.5cm supernatant water depth) (.086 meters/hr)
source water changed to surface well
2009-11-05
9.00 L/hr (14.5cm supernatant water depth) (.0335 meters/hr) 18.95 L/hr (20cm supernatant water depth)(.077 meters/hr)
19.46 L/hr (18.5cm supernatant water depth) (.079 meters/hr)
2009-12-04
0 L/hr Filter frozen*** by below 0°C weather 0 L/hr Filter frozen*** by below 0°C weather
0 L/hr Filter frozen*** by below 0°C weather
2009-12-07
11.25 L/hr (14.5cm supernatant water depth) (.042 meters/hr) 35 L/hr (20cm supernatant water depth)(.142 meters/hr)
30 L/hr (18.5cm supernatant water depth) (.122 meters/hr)
2010-01-01
11.25 L/hr (14.5cm supernatant water depth) (.042 meters/hr) 27.7 L/hr (20cm supernatant water depth)(.113 meters/hr)
28.8 L/hr (18.5cm supernatant water depth) (.117 meters/hr)
2010-01-09
8.37 L/hr (14.5cm supernatant water depth) (.031 meters/hr) 32.7 L/hr (20cm supernatant water depth)(.133 meters/hr)
27.7 L/hr (18.5cm supernatant water depth) (.112 meters/hr)
2010-02-07
9.47 L/hr (14.5cm supernatant water depth) (.035 meters/hr) 24 L/hr (20cm supernatant water depth)(.098 meters/hr)
25.74 L/hr (18.5cm supernatant water depth) (.105 meters/hr)
2010-03-01
8.47 L/hr (14.5cm supernatant water depth) (.032 meters/hr) 24 L/hr (20cm supernatant water depth)(.098 meters/hr)
25.74 L/hr (18.5cm supernatant water depth) (.105 meters/hr)
2010-03-26
8.47 L/hr (14.5cm supernatant water depth) (.032 meters/hr) 24 L/hr (20cm supernatant water depth)(.098 meters/hr)
24.25 L/hr (18.5cm supernatant water depth) (.099 meters/hr)
2010-04-30
10.3 L/hr (14.5cm supernatant water depth) (.038 meters/hr) 29 L/hr (20cm supernatant water depth)(.118 meters/hr)
34 L/hr (18.5cm supernatant water depth) (.139 meters/hr)
2010-09-16
11.15 L/hr (14.5cm supernatant water depth) (.0416 meters/hr) 26.4 L/hr (20cm supernatant water depth)(.108 meters/hr)
28.2 L/hr (18.5cm supernatant water depth) (.115 meters/hr)
2010-12-19
16L/hr (14.5cm supernatant water depth) (.0597 meters/hr) 28 L/hr (20cm supernatant water depth)(.1142 meters/hr)
33 L/hr (18.5cm supernatant water depth) (.1346 meters/hr)
2011-02-06
12.2L/hr (14.5cm supernatant water depth) (.0455 meters/hr) 22.29 L/hr (20cm supernatant water depth)(.091 meters/hr)
27.23 L/hr (18.5cm supernatant water depth) (.111 meters/hr)
2011-03-08
13.56L/hr (14.5cm supernatant water depth) (.0506 meters/hr) 26.67 L/hr (20cm supernatant water depth)(.1087 meters/hr)
28.24 L/hr (18.5cm supernatant water depth) (.115 meters/hr)
2011-04-16
10.64L/hr (14.5cm supernatant water depth) (.040 meters/hr) 32.21 L/hr (20cm supernatant water depth)(.131 meters/hr)
31.86 L/hr (18.5cm supernatant water depth) (.130 meters/hr)
2011-07-02
16.14L/hr (14.5cm supernatant water depth) (.060 meters/hr) 38.71 L/hr (20cm supernatant water depth)(.158 meters/hr)
41.62 L/hr (18.5cm supernatant water depth) (.170 meters/hr)
2011-09-14
12 L/hr (14.5cm supernatant water depth) (.0448 meters/hr) 28.685 L/hr (20cm supernatant water depth)(.117 meters/hr)
32.8 L/hr (18.5cm supernatant water depth) (.1337 meters/hr)
2011-11-25
10.48 L/hr (14.5cm supernatant water depth) (.039 meters/hr) 44.31 L/hr (20cm supernatant water depth)(.181 meters/hr)
31.86 L/hr (18.5cm supernatant water depth) (.130 meters/hr)
2012-03-06
15 L/hr (14.5cm supernatant water depth) (.056 meters/hr) 58.42 L/hr (20cm supernatant water depth)(.238 meters/hr)
37.9 L/hr (18.5cm supernatant water depth) (.177 meters/hr)
2012-08-09
13.14 L/hr (14.5cm supernatant water depth) (.049 meters/hr) 42.85 L/hr (20cm supernatant water depth)(.174 meters/hr)
43.9 L/hr (18.5cm supernatant water depth) (.179 meters/hr)
2012-10-03
10.98 L/hr (14.5cm supernatant water depth) (.041 meters/hr) 48 L/hr (20cm supernatant water depth) (.196 meters/hr)
28.57 L/hr (18.5cm supernatant water depth) (.117 meters/hr)
2013-04-30
10.00 L/hr (14.5cm supernatant water depth) (.037 meters/hr) 51.4 L/hr (20cm supernatant water depth) (.192 meters/hr)
42.4 L/hr (18.5cm supernatant water depth) (.158 meters/hr)
2013-08-27
12.32L/hr (14.5cm supernatant water depth) (.046 meters/hr) 33.96 L/hr (20cm supernatant water depth) (.139 meters/hr)
37.8 L/hr (18.5cm supernatant water depth) (.154 meters/hr)
2014-03-13
25L/hr (14.5cm supernatant water depth) (.093 meters/hr) 36 L/hr (20cm supernatant water depth) (.147 meters/hr)
37.5 L/hr (18.5cm supernatant water depth) (.153 meters/hr)
2014-10-09
26.86L/hr (14.5cm supernatant water depth) (.100 meters/hr) 34.6 L/hr (20cm supernatant water depth) (.141 meters/hr)
30 L/hr (18.5cm supernatant water depth) (.122 meters/hr)
2015-04-05
FLOW SUMMARY FOR FILTER 4 AND FILTER 5 *
Filter 4 (3rd configuration)
.45 mm effective size bottom sand 600 lbs
.24 mm effective size top sand 80 lbs
dc pump is used to recirculate water
filters roof water from composition roof
sand surface area: .26791 sq. m.
container depth 32 inches
started 2011-11-01
Filter 5
.25 mm effective size bottom sand 700 lbs
.15 mm effective size top sand 150 lbs
filters roof water from composition roof
sand surface area: .2452 sq. m.
container depth 40 inches
started 2012-05-01
Date
30 L/hr (18cm supernatant water depth) (.112 meters/hr) 37.9 L/hr (22cm supernatant water depth) (.154 meters/hr) 2012-08-09
31.101 L/hr (18cm supernatant water depth) (.116 meters/hr) 28.4 L/hr (22cm supernatant water depth) (.1158 meters/hr) 2012-09-27
28 L/hr (18cm supernatant water depth) (.105 meters/hr)
first day of temps below 4° C (40° F) at night this season
29 L/hr (22cm supernatant water depth) (.118 meters/hr)
first day of temps below 4° C at night this season
2012-10-03
40 L/hr (18cm supernatant water depth) (.149 meters/hr) 3.7 L/hr (22cm supernatant water depth) (.015 meters/hr) first flush diverter malfunction; turbid water clogged filter 2013-04-30
92 L/hr (18cm supernatant water depth) (.345 meters/hr) sand changed. .30 mm effective size. May 2013 24 L/hr (22cm supernatant water depth) (.099 meters/hr) sand changed, .25 mm effective size. May 2013 2013-08-27
75 L/hr (18cm supernatant water depth) (.280 meters/hr) sand changed. .30 mm effective size. May 2013 13.35 L/hr (22cm supernatant water depth) (.054 meters/hr) sand changed, .25 mm effective size. May 2013 2014-03-13
45 L/hr (18cm supernatant water depth) (.168 meters/hr) sand changed. .30 mm effective size. May 2013 16.98 L/hr (22cm supernatant water depth) (.069 meters/hr) sand changed, .25 mm effective size. May 2013 2014-10-09
56.25 L/hr (18cm supernatant water depth) (.210 meters/hr) sand changed. .30 mm effective size. May 2013 9 L/hr (22cm supernatant water depth) (.037 meters/hr) sand changed, .25 mm effective size. May 2013 2015-04-05
*Filter 4 and 5 are the newest filters.
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Update, July 15, 2021

Wow, last month we wrote that the weather here has been “normal”. Nothing could be further from the truth. We had 104 degrees Fahrenheit here June 28, 2021, and that was in the forest in total shade. So hot it destroyed foliage on sword ferns, trees, and salmonberry bushes here. Ungodly heat. All-time record high. Only one day, though that was enough to last me the rest of my life. Its very dry now 65 percent humidity outside. We have lots of water stored up, though. and much of it already filtered.

Filter one is still running.

The new filter output on the fish pond is gradually improving. So far, looks good. All the other pond filters are still running and the water in all the ponds is crystal clear. No mosquitoes, either. Lots of dragon flies. Some very large 2 inches; some very small less than 1 inch long.

We’ll have updates as the test on the new pond filter continues.

We have noticed, over the past 11 years, that water flowing onto the surface of a pond from an “un-ripe filter, will often have foam, or extensive amounts of bubbles forming. That water, being tested, has been full of bacteria, and other nasty stuff. Water flowing from a fully functioning slow sand filter onto the surface of a pond and splashing, and producing no foam or bubbles, is usually very pure. All of our ponds have very pure water. We use an overflow that allows the unfiltered water that doesn’t make it through the filter, to flow back into the pond; thereby adding oxygen to the pond, from the splashing, and avoiding water loss. Since the filters run 24/7, the water in these ponds is filtered over, and over and over again, even though only a tiny dribble flows from the filtered water outlet. Each pond filter has 2 outlets, filtered, and overflow.

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Blog update June 18, 2021

Filter 1 is still working, and is in the process of being tested again. We are running water through it and hope to be able to have a professional testing done soon. Another pond filter will be put together this year. This will filter pond water supporting 5 medium sized fish. As we get information we will post it here on this blog.

As of June 18, 2021 we have the donation page working. Its title is “Slow sand water filter construction and operation (a summary from this blog) PDF: $7.50”. There’s a link in the header of every page. All our pages are secure, and the donation is via PayPal. We still don’t have ads on this blog, and the content of this blog is not dictated by advertisers. We are paying for all the hosting and computer expenses from our retirement income. These costs have gone up exponentially. At some point in time we will either need to have ads on this blog, obtain enough donations to pay for expenses, or simply shut it down. All our experience and discoveries will then not be available.

The weather here has been “normal”. Precipitation, and temperatures have been “normal”. We are currently starting a dry spell. Hopefully no fires will start.

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May 2021 update

It is now May 22, 2021. All the original slow sand  filters here are still functional. We have 9 slow sand filters running here. Four of them are pond filters. The latest pond filter is still being tested and no data is available. The other 8 filters are still functional. Three of them are pond filters. No tests have been done yet because of the Covid situation.

Filter 1 has been running since 2008:      http://www.slowsandfilter.org/

Filter 2 and 3 have been running since 2009:     http://www.slowsandfilter.org/

Filter 4 and 5 have been running since 2012:     http://www.slowsandfilter.org/

http://www.slowsandfilter.org/filter_five.shtml

Filter 6 (pond filter) has been running since 2010. It runs 24/7 and has an automatic overflow. The water continues to stay crystal clear:     http://www.slowsandfilter.org/pond_filter.html

The other two pond filters have been running about 8 years.

The cistern has been repaired and not leaking; it has been functional since 2010.   http://www.slowsandfilter.org/cistern_page.shtml

We did have some snow this winter. The temperatures were very close to typical for this area (Pacific Northwest Washington state). Hopefully, this year, we will be able to do some water quality testing, and flow rate testing.

 

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2020 slow sand filter update

It’s now December 16, 2020 covid19 is still here and, consequently,  we still cannot have any tests done by commercial testing facilities. Thankfully, the horrific political situation in this country is somewhat calmed down and science will now be respected again. There has been lots of rain here and some wind and 30 degree weather but no snow . . .  yet.

We have one new slow sand filter in operation. This filter cleans water in a 75 gallon outdoor fish tank that has 4 four inch long fish in it. This is a small filter so the results will be interesting. More details later. All but one of the original filters set up here are still running. The first filter, set up in 2007 is still functional and the sand has not been changed for 11 years. It produces crystal clear water from mildly polluted surface runoff from our roof.

The original pond filter set up 9 years ago is still in operation and the water output is crystal clear. More later.

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Slow sand filter update August 8, 2020

All of the original filters except one are still active and running. As of last month, this blog has been here for 12 years. All this time we have been studying and carefully observing the ability of naturally occurring processes to effectively remove bacteria, viruses, and some chemical contaminants from water. We know this works, because of science. There are hundreds of others who have found similar results. On this blog and the associated websites we have detailed information about our experience. We also have a 30 plus page write-up of the entire process available in pdf format.

Sadly, we are still dealing with the Covid19 pandemic here in Western Washington state. We have been in quarantine. We were extremely ill two months ago. Two tests for covid19 came out negative, for us, and we have been healthy since the illness. We are, so far, lucky. There are still too many people who refuse to wear masks, and want to continue as if there is no problem whatsoever. Sad, indeed. We have highly limited access to any testing facilities, although it is possible shop in some stores as long as you wear a mask. As soon as possible we will have some tests done on the filters here. It may be quite some time before we can have any professional testing done on any of the filters here.

Because we have had supplies here before the pandemic, we now have two newly built slow sand filters cleaning water in fish tanks. One filter is serving a 10 gallon aquarium. It has been running for 6 months. No tests yet, but the water has been kept clean and totally odor free; and the fish are quite healthy. We also have a 100 gallon pond with a small slow sand filter serving it, just started. More later. Please; stay safe.

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Update for May 2020

All but one of the slow sand filters here are still working. All of the damage to the cistern has been repaired. Filter 1, which was started in 2007 and first tested in 2008 is still running. No  tests have been possible on the filters because of the situation with covid19.

This year has been horrific world wide. We’ve been in quarantine for 3 months now. The covid19 virus has caused world wide chaos and loss of life. Compound that by race riots here in the U.S.  .  Keep in mind that slow sand filters do remove viruses from water. This has been shown time and time again.

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Update for 2019

As of August 26, 2019 most of the winter storm damage from last year’s snow and ice has been repaired. The cistern roof collapsed under  the weight of the snow. Pipes were broken and water contaminated. The repair work was difficult and time consuming. There is still more work to do, but 6 of the original filters are now functional. The filters feeding the cistern have cleaned the water and we will do a test as time and finances permit. We are forecast to have extended dry warm weather which will require us to shut down the pumps till the fire danger subsides. More updates will follow.

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Slow sand filter update

It is now June 15, 2019; and this blog is approaching its 11th year on the net documenting our studies of slow sand filters. All but one of the filters are still running, including two of the pond filters. ( as we posted years before, the 5 gallon filters are not running and have not been for some time; as they did not work). We had an extensive amount of structural damage from this winter’s record snowfall, and we are still working on repairing that damage.  Other climate related damage is slowly destroying the forest here, and in other places in Washington state. Hemlock and fir trees are dying all over the area:

Emerging Issues with Western Hemlock and Douglas-fir

this will likely adversely affect our ecosystem here beyond repair. Damage to the microbes necessary to make a slow sand filter ( and natural water filtration ) work may very well occur. This is a SERIOUS problem. Read the info at the link; its from trusted sources. No “alternative facts” here.

We will post more info as time permits.

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Slow sand filter video

Here is a link to a video on YouTube of the first filter we set up (Filter 1). It was uploaded in 2007:

https://www.youtube.com/watch?v=1ca6ZbZePBY

Now the story of the video:

In 2007, we uploaded a video of one of our slow sand filters to YouTube. From a website claiming to have “free” music we downloaded a music track to put on the video. This was 12 years ago. The website claimed all their music was free to use without any copyright issues.

Fast forward to 2018: we get a note from YouTube that someone claimed to have copyright to the video because of the music; well “copyright” to be paid a certain amount for each view.  At that point in time we had upwards of 200, 000 views on the video and hundreds, to thousands of views a month. Since our purpose is not exactly to “make money” from views, we decided to take the music off of the video. No problem. . . .   well yes – problem. The references and links that were in place all over the net were no longer valid because YouTube changes the address of the video if you remove music from it. Of course, (we were told) we could just leave the music on the video and then YouTube would leave it alone and we’d still have our place and the links would all be good; but the unknown person/persons claiming copyright would still be making money for every hit to the video. We were told that the music was ok to leave there only if all the money from the hits went to this unnamed entity. Now were the hits due to the music, or the slow sand filter content. Quite frankly, there were 50 or 60 comments saying the music was horrible, and stupid; and yes it was. Ok, enough of that. Let this be a warning: NEVER trust any source unless you are 100 percent sure the music is free.

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