# 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:** 20\ **Page:** 1
**Author:** ![Grrr](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/grrr/32/146_2.png) [@Grrr](https://boards.straightdope.com/u/Grrr)\ **Post date:** [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/717342/1 "2015-04-10T16:23:18Z")
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? ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [April 10, 2015, 4:30pm UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/2 "2015-04-10T16:30:59Z")
Look up “Greywater” ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [April 10, 2015, 4:43pm UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/3 "2015-04-10T16:43:43Z")
> [@Shakes](#): > > Why the heck aren’t we doing this already? Water is relatively cheap (we get ours from a well) and the processing to reuse/divert gray-water has some cost involved. We use rain-barrels to collect our gutter water. That gets used to water gardens, etc. ---
**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 10, 2015, 4:52pm UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/4 "2015-04-10T16:52:55Z")
In the bad old days people washed by filling up a tub with water, and when one person got done the next crawled in. How’s that for recycling? What the OP suggests is doable, but water is so freely and cheaply available in most areas there has not been incentive to develop such systems. ---
**Author:** ![Valgard](https://avatars.discourse-cdn.com/v4/letter/v/7feea3/32.png) [@Valgard](https://boards.straightdope.com/u/Valgard)\ **Post date:** [April 10, 2015, 5:19pm UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/5 "2015-04-10T17:19:20Z")
There was a new article a while ago regarding a shower that does exactly this. It collects, cleans and reuses the runoff so you only need a few gallons of water to run the shower continuously. Here you go: > **[Futuristic water-recycling shower cuts bills by over $1,000 | CNN Business](https://www.cnn.com/2013/11/11/tech/innovation/futuristic-water-recycling-shower-orbsys/)** > > Want to cut your bills by $1000? Invest in an OrbSys shower, the shower that recycles 90% of water and 80% energy every time you wash And it’s actually in use in a coastal bathing area in Sweden. ---
**Author:** ![Tom\_Tildrum](https://avatars.discourse-cdn.com/v4/letter/t/e95f7d/32.png) [@Tom\_Tildrum](https://boards.straightdope.com/u/Tom_Tildrum)\ **Post date:** [April 10, 2015, 5:28pm UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/6 "2015-04-10T17:28:16Z")
Down that road lies Arrakis and the stillsuit. ---
**Author:** ![usedtobe](https://avatars.discourse-cdn.com/v4/letter/u/ec9cab/32.png) [@usedtobe](https://boards.straightdope.com/u/usedtobe)\ **Post date:** [April 11, 2015, 12:10am UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/7 "2015-04-11T00:10:25Z")
Aside from the need to re-plumb pretty much every residence (good luck with those condo towers and houses built on slabs), it is perfectly doable. And massive desalination plants are also doable. It’s just money… ---
**Author:** ![Omar\_Little](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/omar_little/32/269_2.png) [@Omar\_Little](https://boards.straightdope.com/u/Omar_Little)\ **Post date:** [April 11, 2015, 12:23am UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/8 "2015-04-11T00:23:32Z")
Don’t most municipal sewer water systems treat the wastewater and pump it back into the municipal water system? So instead of doing it on an individual house based system, it’s done city wide. ---
**Author:** ![Baffle](https://avatars.discourse-cdn.com/v4/letter/b/dec6dc/32.png) [@Baffle](https://boards.straightdope.com/u/Baffle)\ **Post date:** [April 11, 2015, 12:28am UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/9 "2015-04-11T00:28:24Z")
> [@Omar\_Little](#): > > Don’t most municipal sewer water systems treat the wastewater and pump it back into the municipal water system? So instead of doing it on an individual house based system, it’s done city wide. I don’t know about _most_. I’ve personally never heard of it happening, and it certainly doesn’t happen around here (of course, we are sitting on the world’s biggest supply of fresh water…) Here, our water is pumped from a series of city wells, and once the sewage is treated, it’s discharged to the river. Cities downstream do get their water from that same river. (Sorry, Brantford.) But it’s not a closed loop. Treated sewage is supposed to be drinkable, though since we keep finding pesky contaminants like pharmaceuticals and cosmetic products in it, I’m kind of leery of the thought. ---
**Author:** ![Mangosteen](https://avatars.discourse-cdn.com/v4/letter/m/6a8cbe/32.png) [@Mangosteen](https://boards.straightdope.com/u/Mangosteen)\ **Post date:** [April 11, 2015, 2:09am UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/10 "2015-04-11T02:09:15Z")
Going through the hassle of recycling your shower water is a lot of work. I don’t know how big your yard is, but a rain water catchment tank might be a better way to go. The tank I have at my home in Hawaii holds about 10,000 gallons. Its a 20 foot wide 6 foot tall cylinder. We sometimes get as many as 200 inches of rain a year. This means about 1.5 million gallons of rain water falls on my 40 x 40 roof each year. Obviously, the tank is always full. Rain gutters send the water to the tank. A solar powered electric pump sends the tank water into my home. The water goes through a filter before it enters the house. We are not connected to the county water system. Dallas gets over 30 inches of rain a year. If your roof is 36 x 36 feet, this means that about 25,000 gallons of rain water falls on your home each year. The formula is, for example, if the measurement of your roof is 36 x 36 feet. including the eaves, your roof area is 1296 square feet. Multiply this by 0.625 gallons of water per inch of rainfall in your area. That is 1296 sq. ft. x 0.625 = 810 gallons per inch of rainfall. Twenty-Five thousand gallons of “free” water a year is a lot of water even if you don’t bother to filter it. It would certainly seem enough for your landscape needs. Here’s the catchment tank. (Yes, its ugly, but one can plant bushes around it or paint it or? [![](https://img.photobucket.com/albums/v61/GarySiegel/Pepeekeo%20August%202011/2014-01-19%2009.37.11_zpsllnpknr7.jpg) ](https://img.photobucket.com/albums/v61/GarySiegel/Pepeekeo%20August%202011/2014-01-19%2009.37.11_zpsllnpknr7.jpg) ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [April 11, 2015, 2:41am UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/11 "2015-04-11T02:41:43Z")
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. ---
**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 11, 2015, 2:54am UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/12 "2015-04-11T02:54:42Z")
> [@Omar\_Little](#): > > Don’t most municipal sewer water systems treat the wastewater and pump it back into the municipal water system? So instead of doing it on an individual house based system, it’s done city wide. In Milwaukee (and probably most/all other cities around the Great Lakes) we clean and then dump our water into the lake. Then when we need water we draw it off the lake, treat it and send it back out to the city. Potable water (at least around here) is very cheap. Probably far too cheap to make filtering it, in house, a viable option. For a while I tried that ‘if it’s brown’ thing. Then I did the math and found that if I save three flushes a day it works out to a savings of something like five dollars a year. Now, what I’d like to see is a heat exchange between the shower drain and the cold water intake on the water heater. Reusing shower water to clean your clothes probably won’t save much money, but if you can extract some heat out of it, I’d guess you could save 5 or 10 dollar a month. The problem I foresee with that is that it would probably get clogged with grease and hair rather quickly. You could put in a bypass so it doesn’t backup, but still, it would render it useless rather quickly. Having said all that, I know some people re-plumb their dishwasher so that the drain water goes outside and waters their (flower only) garden. That’s an easy one since dishwasher tend to be on an outside wall. My concern would be that the drain line would freeze in winter. I recall an episode of Ask This Old House where they used the drain from a washing machine and ran it to a pop up/drip irrigation system that fed plants in the entire back yard. ETA, that was easy to find: [http://www.thisoldhouse.com/toh/video/0,,20803344,00.html](http://www.thisoldhouse.com/toh/video/0,,20803344,00.html) ---
**Author:** ![grude](https://avatars.discourse-cdn.com/v4/letter/g/e47774/32.png) [@grude](https://boards.straightdope.com/u/grude)\ **Post date:** [April 11, 2015, 3:16am UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/13 "2015-04-11T03:16:03Z")
Our set up does this already, everything but the toilet drains to “streams” in the yard, toilet goes to a septic tank. These “streams” run above and below our property, and everyone else dumps grey water in there too. [http://www.newsday.co.tt/galeria/2013-04-08-8-2\_A\_LAVENTILLE\_SUNDAY\_(2).jpg](http://www.newsday.co.tt/galeria/2013-04-08-8-2_A_LAVENTILLE_SUNDAY_(2).jpg) I think at the bottom of the hill it joins a river. ---
**Author:** ![Baffle](https://avatars.discourse-cdn.com/v4/letter/b/dec6dc/32.png) [@Baffle](https://boards.straightdope.com/u/Baffle)\ **Post date:** [April 11, 2015, 5:00am UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/14 "2015-04-11T05:00:48Z")
> [@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. Sure thing. Run those pumps as much as you can afford to. ---
**Author:** ![DrDeth](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@DrDeth](https://boards.straightdope.com/u/DrDeth)\ **Post date:** [April 11, 2015, 7:10am UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/15 "2015-04-11T07:10:10Z")
> [@Senegoid](#): > > I haven’t heard of treated sewage water getting recycled back into the regular municipal water supply. It can be done and has been done on a very limited case. Sometimes this is called “4th stage” water treatment. It’s far cheaper and better for the environment than desalinization, but people are idiots. As far as the Op’s shower water, the issue is what kind of detergent, etc you wash with. Most would be hard to filter and bad for the environment. But at the very least I suggest putting a large bucket in the shower to catch the pure(ish) water that is used while the water gets hot. ---
**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, 9:04am UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/16 "2015-04-11T09:04:34Z")
Waste water gets treated and returned to the system all over the world. Here in the UK, it is not so direct usually, but that may well change: > [@](#): > > Recycled toilet waste could be introduced to London’s tap water, under plans being considered by Thames Water. > The company has launched a consultation on the idea of drinking sewage water which has been treated, put back in the Thames and retreated. > A strategy document said the technique was “common practice” across the world. > [@](#): > > in towns such as Oxford upstream from London there was "a degree of waste water recycling going on now > **[London 'could drink treated sewage' - Thames Water](https://www.bbc.co.uk/news/uk-england-london-22479216)** > > Recycled toilet waste could be introduced to London's tap water under plans being considered by Thames Water. > [@](#): > > Every day, Thames Water abstracts / extracts, treats and supplies 2.6 gigalitres (2.6×109 litres) of potable tap water from 102 water treatment works via 288 clean water pumping stations through 31,100 km (19,300 mi) of managed water mains to 9 million customers (3.6 million properties) across London and the Thames Valley.[19] It maintains 30 raw water reservoirs and 235 underground service reservoirs.[2] > > Likewise, it daily removes, treats and disposes 4.4 gigalitres (4.4×109 litres) of wastewater from 15 million customers (5.1 million properties) using 2530 sewage pumping stations through 108,000 km (67,000 mi) of managed sewerage mains to 350 sewage treatment works across an area of 13,000 km2 (5,000 sq mi) of South England.[19] On 1 October 2011, it adopted 40,000 km (25,000 mi) - an additional 60% - of private sewers and lateral drains to add to its then stock of 68,000 km (42,000 mi) giving the current total of 108,000 km (67,000 mi) managed sewerage mains. Before 1 October 2016, it is obliged to adopt 5,000+ private sewage pumping stations to add to its current stock of 2530 managed sewage pumping stations [2][20] > > Thames Water produces biosolid fertiliser as a by-product from the waste treatment, and supplies this to local farms. It also recovers phosphates - an increasingly important source of a dwindling naturally-occurring mineral. > **[Thames Water](https://en.wikipedia.org/wiki/Thames_Water)** > > Thames Water Utilities Ltd, trading as Thames Water, is a British private utility company responsible for the water supply and waste water treatment in most of Greater London, Luton, the Thames Valley, Surrey, Gloucestershire, north Wiltshire, far west Kent, and some other parts of England. Like other water companies, it has a monopoly in the regions it serves. > With origins dating back to the formation of the New River Company in 1609, Thames Water was established in 1989 during privatisation ... ---
**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 11, 2015, 1:22pm UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/17 "2015-04-11T13:22:42Z")
> [@Senegoid](#): > > 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. The water from my well goes into my septic system, which means it goes back into the local ground. Planted my garden on top of the drainfield, so I’m recycling some of the organic components back into food. Lovely closed loop. As long as none of the region’s heavy industry contaminates the ground water. Superfund sites are not good neighbors. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [April 11, 2015, 1:50pm UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/18 "2015-04-11T13:50:43Z")
> [@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. I’m surrounded by the Great Lakes. Water we use gets cleaned, treated, and dumped back into the lake. > [@](#): > > 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. why? so they can continue to mismanage water usage? ---
**Author:** ![Your\_Great\_Darsh\_Face](https://avatars.discourse-cdn.com/v4/letter/y/ac8455/32.png) [@Your\_Great\_Darsh\_Face](https://boards.straightdope.com/u/Your_Great_Darsh_Face)\ **Post date:** [April 11, 2015, 2:20pm UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/19 "2015-04-11T14:20:31Z")
> [@Rudyard Kipling](#): > > My privy and well drain into each other > After the custom of Christendie. . . . > Fevers and fluxes are wasting my mother. > Why has the Lord afflicted me? > The Saints are helpless for all I offer– > So are the clergy I used to fee. > Henceforward I keep my cash in my coffer, > Because the Lord has afflicted me. “Natural Theology”, stanza III, “Mediæval” ---
**Author:** ![DrDeth](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@DrDeth](https://boards.straightdope.com/u/DrDeth)\ **Post date:** [April 11, 2015, 7:32pm UTC](https://boards.straightdope.com/t/how-hard-would-it-be-to-filter-used-shower-bath-water-to-use-again-for-cleaning/717342/20 "2015-04-11T19:32:20Z")
> [@jz78817](#): > > why? so they can continue to mismanage water usage? Yeah, so CA can use most of it’s water growing food for the rest of the country. Only about 10% of our water is used for residential. [Next 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=2)