View Full Version : Biosand Filters, easy to make purifier for water

Christine Breese
23rd August 2011, 16:42
We're building a sustainable community planned to be off the grid in a year, and I have been doing some research on creating sand filtering for purifying water that comes off the rooftops and other sources, you might be able to use this info http://www.biosandfilter.org/biosandfilter/index.php/item/229 and there are other sites if you search online with this info. Good to be able to collect your rainwater and use it in the future since electric well pumps might not be working, or if you're using a source of water from streams of springs and can gravity feed it, this is a way to purify it and build a cheap no electric filter.

Basically, you put a layer of gravel in the bottom of a container, (then carbon/charcoal in the middle layer if it's water you want to drink), and sand in the top largest layer. Works great from what I'm finding online. We're going to be doing sand filters with gravel (no charcoal) for reusing shower water in the toilet tanks, so that it's clean but doesn't have to be purified to drinking level, and making other sand filters WITH carbon for filtering drinking water.

When it rains here in Ecuador, the roofs of all the buildings can act as cisterns to collect tankloads of water, but it has to be purified to drink, as there's bird poop and such on the roofs sometimes, never know. Anyway, just wanted to pass this resource on to you. Hope you can use it!

24th August 2011, 03:25
Some rainwater collection systems here in Texas have a valve which discards the first water off the roof and then begins filling the tanks. The diverted water can be used for agricultural irrigation. Another consideration is the roofing material. This is a greater concern among natural builders. Usually a simple filter and a UV sterilizer is all that is used. However, in my opinion, there is nothing like a lab test to set your mind to rest. Pollution drift or weather modification programs can add another facet.

4th July 2012, 03:30
This is an older thread, but I figured I'd comment.

As much as biosand filters excite me, there is always more to technology than just using it. I know some of this because I used to work for a large NGO in their water and sanitation sector. Consider this fact: 80% of all wells built in Rwanda don't work today. Why? Because donors come in and put their egoic needs first, over the people's, and pick sexy new shiny projects to give to people. Then, very little operation, maintenance and hygiene programs are put in place, and a short while after the donor leaves, a valve breaks, and no one can fix it, and the whole thing goes to waste.

Basically, sand filters work. However, the sand must be rotated often. So if you put one on every house connected to a water collection system, that's wonderful, but be prepared to have the humanpower and materials to replace the sand every so often depending on the volume of sand, volume of water being cleaned and turbidity of the water. Also be prepared to have people operate and maintain the filters and roofs and buolding materials. I hope this helps. Loving wishes for your sustainable community.