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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