ecoexist store

2008
Sep 25

My wife, of course, likes to take baths. My son is afraid of the shower so he takes baths. I try to conserve water wherever I can and even take a 5 Gallon Bucket into the shower with me to collect the water when it’s heating up, and while I’m lathering up (5th paragraph down in the post). In a way I am a bit hypocritical in the sense that I have a pool, and pools aren’t eco-friendly or promote water conservation. I’ve been trying to think of ways to offset the extra consumption of water due to the pool – which leads me back to the bath water.


Our entire yard was cemented over a long time ago. It’s both a blessing and a curse in that it’s nice to not have to mow a lawn or do extra yard work and we save a lot of water by not having grass or other plant life, but it retains heat in a horrible way and on extremely hot days it may not cool down until 2am. It’s essentially a “hose down” yard but if it gets hosed down a few times a week then we aren’t saving any water over a grassed yard. We have two large dogs, so it needs to be hosed down often. I have been looking for a way to clean the bath water well enough to be able to use it to hose down the yard – thus re-purposing a large amount of used water.


I bought a 5.5GPM pump a while back from a used electronics store and I have lots of marine batteries to hook it up to. I also have three 55 gallon barrels which I can pump the water into. I wanted to build something to filter the water before it made it into the barrel, because it’s easier at that point that to filter it while it’s being siphoned out for use. Here’s what I came up with – which was inspired by an episode of Renovation Nation where a homeowner built something similar to filter rainwater:



  • 5 gallon bucket – can be bought at a hardware store for under $5, but most people already have one laying around

  • a 1 1/2″ pipe connector – male and female – for the drain hole. About $4 from the hardware store

  • two 2″ rubber gaskets for the pipe connectors, to seal around the hole. About $2.50 for a two pack (check in the faucet repair area in the plumbing section)

  • bag of sand – it was harder to find than I thought. About $4.50. This will do the core of the filtration

  • bag of pea gravel – about $3.50. This is used to keep the outlet from getting clogged up and to level out the bottom of the inside of the filter

  • Koi pond filter – also found at the hardware store in the outdoor garden center by the pond equipment. It was the most expensive piece @ $10. This is used to keep the sand in the filter, and also does some large particle filtering – hair and whatnot

  • Optional – a pack of terry cloths, about $2.50. I used them mainly for additional protection from the sand coming out and also to prevent the Koi pond filters from getting clogged up with sand.



Here are the step-by-step pictures of the project as I constructed the filter. You’ll notice that I had already cut the hole and put the pipe fitting in the bucket at this point. Also, before the pipe fitting is installed you’ll need to drill a few holes in the top pipe fitting (the piece that is in the bucket when assembled, not sticking out of the bottom) for complete drainage.



The parts list




Wash the pea gravel to get all the dirt off and fill the bottom of the bucket with enough pea gravel to make it level with the top of the pipe connector (the one that you drilled holes into before assembling)




I put a terry cloth rag on top of the gravel, in an attempt to make cleanup easier later




The Koi pond filter comes in two pieces, the denser one goes in at this point (it’s like a scrubber pad). These should have been cut to fit the bucket, but I was impatient and wanted to try it out




I put another terry cloth on top of that – this is important to help keep the sand out of the filter as much as possible




Put about 4″ of sand on top and level it out




Then another terry cloth, if you want to




Then the other half of the Koi pond filter




Then I threw on another terry cloth on top of all that. Now it’s time for the test. It’s best if you let clean water run through it for a few minutes to clean out all the dirt that needs to be washed out of the filter initially. It’s like a carbon filter for your refrigerator that also needs to have water run through it before it can be used. In hindsight I should have washed the pebbles before putting them in the filter, but it’s a lesson learned. Here’s my initial test run. The pipe fitting fits perfectly into the opening on the barrel it’s sitting on in the picture:




I suppose a disclaimer is in order. This filter is for NON-potable water only! Do not drink it.

22 Responses

  1. Recycling - doing as much as we can | ecoexist.net Says:

    […] only do we try to recycle water (and even more water), but we also try to recycle as much garbage as possible. There are two adults, a child, two medium […]

  2. Water reclaimation overflow | ecoexist.net Says:

    […] paragraph down) to capture the cold water while I’m waiting for the water to warm up, and I reclaim bath water when I can. I’ve also have been wanting to capture the washing machine discharge but […]

  3. Greta Says:

    Hi, I read this with great interest given that commercial sold versions of grey water treatment systems in Australia are pretty expensive, and yet I know people have designed similar things for their yards to water the plants. In fact, the first time I ever saw a system like this was in Nepal used to purify water for drinking and…well…I had no stomach problems. But aside from that, how has this worked since you built it? And how often have you had to clean or replace the sand and gravel? Is it good for kitchen water (minus grease) and laundry rinse water?

  4. admin Says:

    Hi! Thanks for the question. I may not have quite the answer you’re looking for, but I’ll give you as much information as I have at this time.

    I haven’t really used the filter in about six months. The biggest reason is because my yard is about 95% concrete and I just don’t have a need for as much water as I can potentially collect with the filter. I get almost enough water just by using a 5 gallon bucket in the shower (http://ecoexist.net/archives/4) to water the plants and flush the toilets occasionally. I expect I’ll pick up the filter bucket again when I start planting my garden this spring though. When I did use the filter I would clean the top filter about every 3 filter cycles to get the soap residue out, using the filtered water of course. I’d then rinse out the sand every 7-10 filters, and replace the sand about every 30 filters. One thing I needed to look into improving is that the flow of the filter wasn’t quite fast enough. I was using a 5gpm (19 litres per minute) pump and had to keep turning it off and on so that the filter wouldn’t overflow. Maybe a wider bottomed bucket or something would make it better.

    If you try out this project, then please comment again with your progress and experiences. I’d love to hear how things go. Good luck!

  5. Different view on a water filter | ecoenthusiast Says:

    […] did find an article about a home project for filtering grey water that seems easy, exceptionally cheap, has lots of pictures and instruction, and much more practical […]

  6. Chris Says:

    I basically did the same but instead of a bucket I have a large trash bin, about 3 feet tall and I only have one layer of sand with no filter, just a few layers of cotton t-shirt between the sand and the loose gravel. My sand layer is about 10-12 inches deep. I also bought a 150GPH pump(about 2.5 GPH). I am planning on rebuilding the layers with about 2 inches of activated carbon, but I can’t find a cheap enough supply. On a large scale availability is scarce and expensive.
    I was just using bath water to water my garden but I started to notice that my plants were exhibiting alkaline soil problems Specifically iron deficiency . And further research told me that the additional soapy water was adding alkalinity to the soil which prevents iron uptake. Now I just supplement the water with small amounts of vinegar to acidify (or neutralize) the waste water and all is well. Hopefully the sand filter provides additional benefits.

    What I might start doing is using another pump to cycle the water through the sand filter to increase what I can filter out.

  7. admin Says:

    Wow, that’s some great information! Thanks for sharing it! I think that your idea of using t-shirts is probably easier and cheaper than the filter solution I had in place, I’ll have to give that a try.

  8. Marc Says:

    That is a very interesting and bright concept and it would appear as if it would filter the water very well…thanks for the tip.

  9. John Says:

    Hi there, we who backwash our swimming pools can have a drum or two set up with a pipe running back to the pool. A similar filter of sand and gravel separated with some cloth should be more than enough. As we backwash our pools the water pours into the drum (hidden in the garden) and then trickles back into the pool. The water is already pH balanced and has chemicals etc in it and therefore we’ll also save on chemicals too. It is also not a good idea to pump pool water onto our gardens or down the drain, so put it back where it belongs… in the pool.

  10. admin Says:

    That is a great idea. At my last house I had a pool as well and unfortunately when I back-flushed the filter I was not doing this with my water. Usually I probably dumped only about 50 gallons at a time, but that would have been 50 gallons less from the local water supply. Thanks for posting your comment!

  11. hello! Says:

    This is a great idea! Thank you I am doing this for a science project. But I was wondering where to get the koi pond filter. I cant seem to find any anywhere! Do you know if there is any at Lowes, Home Depot, Walmart, Target, Pet Co? If you could contact me at my email (ggbartolome@gmail.com) that would be a great help to me and my project.
    Mahalo,
    Gabby B.

  12. admin Says:

    Hi, thanks so much for commenting and letting me know the post was of interest to you. I know it has taken me a while to reply so I don’t know if you’re still considering it for your project, but I finally found an example kit online here.

    Please let me know if you do the project and how it goes! Thanks again

  13. Colleen Says:

    Just wondering if you have any problems with the clothes in the filter becoming moldy from holding the moisture?

  14. admin Says:

    Sorry for the extremely late reply on this. The idea is to clean out the filter from time to time (weekly, bi-weekly – depends on use) at which time the cloth would be washed. You could get around having to clean it more often if you don’t use it much if you use an exterior screen material, like a durable window screen instead. Hope that helps!

  15. www.bioinformatics.org Says:

    Something that I by no means really seem to comprehend is why some posts are extremely undesirable – and your own is undoubtedly not!

    Many thanks for sharing a fantastic brief article with us!

  16. eric Says:

    I have a grey water system in my house that i installed myself. I used a filter like this and it worked well but cleaning the filter was a mess. My system collects shower water and washer machine water filters it and runs back to my toilets. It cut my water bill by about 60% .

  17. Fred Stern Says:

    Looking at koi filter media online, would you use black, grey blue , or green. All I can seem to find is those four colors at pond guy or Amazon in half sheets.

  18. Paul Says:

    The only concern I have is that the bottom 1.5″ (or the height of your pipe connector) is not getting any action. It seems like it would be ideal to have the connector flush with the bottom otherwise your pea gravel is not doing anything. If you are concerned with your pea gravel pouring out the bottom you can easily place a small piece of chicken wire (with spacing smaller than your smallest pieces of gravel) over the outlet.

    Otherwise great design! Thanks for the idea!

  19. Kevin Mazzocco Says:

    You do NOT want to nor need to wash out your filter media. As long as water is flowing thru the filter and not sitting stagnant, there will be beneficial bacteria living on the media. Washing the media kills these good bacteria and sets the whole filter back to the starting point, when it was sterile and thus not as effective. This is common knowledge for those who keep fish in aquariums and saves you lots of trouble and heartache. Enjoy!

  20. admin Says:

    Thanks for the tip Kevin, I really appreciate the feedback.

  21. Charles Botswana Says:

    Trying to set up a similar system here in Botswana and came across all your ideas and comments. Thanks guys.

  22. admin Says:

    Thanks Charles. Good luck with your project!

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