# How hard would it be to filter used shower/bath water to use again for cleaning? **URL:** \ **Category:** Factual Questions\ **Created:** [April 10, 2015, 4:23pm UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342 "2015-04-10T16:23:18Z")\ **Posts on this page:** 14\ **Page:** 2
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [April 11, 2015, 10:23pm UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/21 "2015-04-11T22:23:42Z")
I read somewhere that the British Army was more successful than the others in the 18th/19th century, because they discovered that it was a bad idea to put the latrines next to the source of drinking water. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [April 12, 2015, 4:59am UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/22 "2015-04-12T04:59:39Z")
> [@DrDeth](#): > > Yeah, so CA can use most of it’s water growing food for the rest of the country. It is still arguably water mis-management to lavish so much water on the desert. Maybe we could go back to growing food where water occurs naturally? ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [April 12, 2015, 5:11am UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/23 "2015-04-12T05:11:29Z")
> [@Broomstick](#): > > Maybe we could go back to growing food where water occurs naturally? When did we ever stop? ---
**Author:** ![DrDeth](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@DrDeth](https://boards.straightdope.com/u/DrDeth)\ **Post date:** [April 12, 2015, 5:24am UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/24 "2015-04-12T05:24:42Z")
> [@Broomstick](#): > > It is still arguably water mis-management to lavish so much water on the desert. > > Maybe we could go back to growing food where water occurs naturally? not much of it’s really desert and the soil and the weather is right. If you want fresh fruit and veggies all year around and modestly priced stuff, then it needs to be CA. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [April 12, 2015, 11:56am UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/25 "2015-04-12T11:56:32Z")
I remember when fresh fruit and vegees were far more seasonal than they currently are, it’s not a disaster. Rather than destroy ecosystems by diverting all the water to California I’d go back to that. I get most of my vegetables out of my backyard, which is even more moderately priced than the stuff from California. There are also other locations that grow vegetables all year round, or taken together would supply them year round. California is not as indispensable as its residents would like to believe. Ya’ll are a convenience, not a necessity. The rest of us take a look at what happens to the Colorado before it reaches the sea. You’re not getting any more water. You have to learn to live with what you have. ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [April 12, 2015, 1:20pm UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/26 "2015-04-12T13:20:28Z")
> [@Broomstick](#): > > I remember when fresh fruit and vegees were far more seasonal than they currently are, it’s not a disaster. Do you remember when produce cost significantly more than it does today? ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [April 12, 2015, 2:32pm UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/27 "2015-04-12T14:32:30Z")
> [@DrDeth](#): > > not much of it’s really desert and the soil and the weather is right. If you want fresh fruit and veggies all year around and modestly priced stuff, then it needs to be CA. Or Mexico > [@Broomstick](#): > > I remember when fresh fruit and vegees were far more seasonal than they currently are and then we started bringing in fruit from South America during Winter. ---
**Author:** ![Enola\_Gay](https://avatars.discourse-cdn.com/v4/letter/e/3ab097/32.png) [@Enola\_Gay](https://boards.straightdope.com/u/Enola_Gay)\ **Post date:** [April 12, 2015, 2:56pm UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/28 "2015-04-12T14:56:17Z")
> [@Shakes](#): > > Title says it all. > > At the very least, it seems like all that water going down the drain could be used to flush the toilet. Why the heck aren’t we doing this already? I looked into this very recently since I live in drought land. If you want to divert all grey water for recycling, you essentially have to replumb your entire house & have a dual system–one for grey water & one for black water. Additionally, if you plan to use the grey water for watering plants, only organic products can go down the drain–including cleaning products (so no bleach, ammonia, etc). Now it might be possible to divert shower water to the toilet in the same room & since it’s going to the toilet, there would be no need to worry about what products allow down the drain. However, toilets use approximately 3-7 gallons per flush, but showers uses approx 10 gallons per minute, so you’d have a lot more water than you would likely use for toilet flushing, since a 10 minute shower would produce approx 100 gallons of water. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [April 12, 2015, 3:13pm UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/29 "2015-04-12T15:13:58Z")
Very easy to do. The cost of replacing and cleaning the filters makes it impractical. A simple aquarium canister pump with a micron filter will clean over 100 gallons of water an hour. Use some diatomaceous earth and the water will be close to clean enough to drink. It might also clog up from a single bath or shower. Oxidizers could be added to help keep the filter clean and still leave usable cleaning water, but you’d still probably need something the size of a swimming pool filter to avoid frequent cleaning, but the eventual time and cost of replacement will increase. ---
**Author:** ![rbroome](https://avatars.discourse-cdn.com/v4/letter/r/838e76/32.png) [@rbroome](https://boards.straightdope.com/u/rbroome)\ **Post date:** [April 12, 2015, 9:42pm UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/30 "2015-04-12T21:42:27Z")
> [@Senegoid](#): > > I haven’t heard of treated sewage water getting recycled back into the regular municipal water supply. Rather, it might get routed into a separate water supply that is used for municipal landscaping. Or, it might be dumped into a big pond where is soaks into the ground to replenish the local water table or aquifer. > > All you people who aren’t filtering and recycling your sewage water because fresh water is _so cheap_ ought to be recycling and routing that water to California. But California went and hid behind the Rockies. Not our fault. Except for that we would be glad to help… 🙂 ---
**Author:** ![rbroome](https://avatars.discourse-cdn.com/v4/letter/r/838e76/32.png) [@rbroome](https://boards.straightdope.com/u/rbroome)\ **Post date:** [April 12, 2015, 9:46pm UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/31 "2015-04-12T21:46:22Z")
> [@Enola\_Gay](#): > > I looked into this very recently since I live in drought land. If you want to divert all grey water for recycling, you essentially have to replumb your entire house & have a dual system–one for grey water & one for black water. Additionally, if you plan to use the grey water for watering plants, only organic products can go down the drain–including cleaning products (so no bleach, ammonia, etc). > > Now it might be possible to divert shower water to the toilet in the same room & since it’s going to the toilet, there would be no need to worry about what products allow down the drain. However, toilets use approximately 3-7 gallons per flush, but showers uses approx 10 gallons per minute, so you’d have a lot more water than you would likely use for toilet flushing, since a 10 minute shower would produce approx 100 gallons of water. 10 g/min? That is a heck of a shower! 🙂 I assume you meant 10 g/shower. That is more typical. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [April 12, 2015, 11:40pm UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/32 "2015-04-12T23:40:09Z")
> [@Enola\_Gay](#): > > Now it might be possible to divert shower water to the toilet in the same room & since it’s going to the toilet, there would be no need to worry about what products allow down the drain. However, toilets use approximately 3-7 gallons per flush, but showers uses approx 10 gallons per minute, so you’d have a lot more water than you would likely use for toilet flushing, since a 10 minute shower would produce approx 100 gallons of water. So get a sufficiently large reserve tank to store greywater in for later use. I don’t know about you, but I flush the toilet more often than I shower. Just using some of the greywater for flushing is better than using none of it. ---
**Author:** ![Enola\_Gay](https://avatars.discourse-cdn.com/v4/letter/e/3ab097/32.png) [@Enola\_Gay](https://boards.straightdope.com/u/Enola_Gay)\ **Post date:** [April 14, 2015, 2:19pm UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/33 "2015-04-14T14:19:56Z")
> [@rbroome](#): > > 10 g/min? > That is a heck of a shower! 🙂 > I assume you meant 10 g/shower. That is more typical. Average for a regular shower is 7-10 gallons per minute. A bath tub uses 36-50 gallons. [Cite](https://secure.wsscwater.com/home/jsp/content/water-usagechart.faces). > [@Broomstick](#): > > So get a sufficiently large reserve tank to store greywater in for later use. I don’t know about you, but I flush the toilet more often than I shower. > > Just using some of the greywater for flushing is better than using none of it. Yeah it would depend on your set up. In my house, we shower in the master bedroom which is upstairs. Our plumber could only divert the shower water to the toilet in the same room(without replumbing the whole house). But that toilet gets used only once or twice a day. The one that gets flushed the most is the one downstairs since guests use it. But yes recycling some greywater is better than none, provided you can afford to make the necessary plumbing changes (and in my jurisdiction, permits are required–which is always a hassle). IMO new building codes should require a dual plumbing system so all greywater can get recycled. ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [April 14, 2015, 3:13pm UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/34 "2015-04-14T15:13:29Z")
Warning: autoplaying video, click on skip intro. [This](http://www.roca.com.es/ww/index.html?en) washbasin/toilet combo uses the water from the basin for the toilet. [Previous page](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342.md?page=1)