# Using "gray" water for flower garden watering
**URL:** https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613
**Category:** Factual Questions
**Created:** [January 10, 2009, 12:23am UTC](https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613 "2009-01-10T00:23:19Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@NoCoolUserName](https://boards.straightdope.com/u/NoCoolUserName)
#### Post date: [January 10, 2009, 12:23am UTC](https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613/1 "2009-01-10T00:23:19Z")
Every summer our water bill goes up by a factor of 3. I suspect we could eliminate most of that by using outflow from the tub for watering the flowers. Is there hardware to support this directly?
I suspect we would need a large container and a pump, much like those used by people who get their water from a well. How big are those plastic tanks, and what would one + a pump cost?
Should such a system be reasonable, I suspect we could also flush the toilets with the same water, which would be a savings as well–not to mention being eco-friendly.
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### Author:  [@DMC](https://boards.straightdope.com/u/DMC)
#### Post date: [January 10, 2009, 1:12am UTC](https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613/2 "2009-01-10T01:12:46Z")
I would recommend you read [this](http://en.wikipedia.org/wiki/Greywater) before doing anything.
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### Author:  [@Zakalwe](https://boards.straightdope.com/u/Zakalwe)
#### Post date: [January 10, 2009, 1:28am UTC](https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613/3 "2009-01-10T01:28:01Z")
> [@NoCoolUserName](#):
>
> I suspect we could eliminate most of that by using outflow from the tub for watering the flowers.
Don’t know how it works where you are, but around here it wouldn’t help. The majority of my water bill is in fact a sewage charge, but the sewage charge is based on the water input, not a separately metered outflow. In other words, I’m charged for sewage treatment regardless of whether or not I actually put the water back in the system.
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### Author:  [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)
#### Post date: [January 10, 2009, 1:39am UTC](https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613/4 "2009-01-10T01:39:37Z")
It’s not a good water source for plants. Using rinse water from your washing lettuce to eat is completely different than your bath and dish water.
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### Author:  [@susan](https://boards.straightdope.com/u/susan)
#### Post date: [January 10, 2009, 4:29am UTC](https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613/5 "2009-01-10T04:29:23Z")
I throw a few 5-gallon buckets in the shower while the water’s warming up, then put them out in the bathroom while I shower. It’s not gray water, but clean water that would otherwise be wasted.
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### Author:  [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)
#### Post date: [January 10, 2009, 4:40am UTC](https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613/6 "2009-01-10T04:40:31Z")
> [@Zakalwe](#):
>
> the sewage charge is based on the water input, not a separately metered outflow.
It would be difficult to meter wastewater.
Sewage charges here are a flat fee.
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### Author:  [@NinetyWt](https://boards.straightdope.com/u/NinetyWt)
#### Post date: [January 10, 2009, 5:13am UTC](https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613/7 "2009-01-10T05:13:28Z")
> [@carnivorousplant](#):
>
> It would be difficult to meter wastewater.
> Sewage charges here are a flat fee.
It can be done, but is best done on a larger scale (such as one metering station for an entire subdivision). Basing the sewer charge on the amount of water used is standard practice IME.
In some places, you can ask for a separate meter for any water lines used for irrigation. That won’t help the OP though.
If your area gets significant rainfall, you can use rain barrels or bladders to collect rainwater from your roof, to be used for irrigation.
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### Author:  [@Apex\_Rogers](https://boards.straightdope.com/u/Apex_Rogers)
#### Post date: [January 10, 2009, 5:44am UTC](https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613/8 "2009-01-10T05:44:37Z")
> [@Zakalwe](#):
>
> Don’t know how it works where you are, but around here it wouldn’t help. The majority of my water bill is in fact a sewage charge, but the sewage charge is based on the water input, not a separately metered outflow. In other words, I’m charged for sewage treatment regardless of whether or not I actually put the water back in the system.
It would still help the OP since the total water drawn from the system would be less. Instead of drawing additional water to irrigate the plants, the OP would be re-using water that was already dispensed. That being said, I do question the feasibility of the OP’s proposed idea as I’m not sure soap is good for plants/soil (although would it be of high enough concentration to matter?). I do like **susan’s** idea to collect the water as the shower warms up.
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### Author:  [@Xema](https://boards.straightdope.com/u/Xema)
#### Post date: [January 10, 2009, 3:57pm UTC](https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613/9 "2009-01-10T15:57:06Z")
> [@susan](#):
>
> I throw a few 5-gallon buckets in the shower while the water’s warming up, then put them out in the bathroom while I shower.
So you must run more than 5 gal through the shower before it’s warm? Yipes.
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### Author:  [@NinetyWt](https://boards.straightdope.com/u/NinetyWt)
#### Post date: [January 10, 2009, 5:43pm UTC](https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613/10 "2009-01-10T17:43:19Z")
> [@Xema](#):
>
> So you must run more than 5 gal through the shower before it’s warm? Yipes.
Might not take that long, depending on what kind of fixture used:
> [@](#):
>
> Typical non-conserving showerheads have flow rates of 5 to 8 gallons per minute, meaning that a typical 5-minute shower would send about 25 - 40 gallons of fresh water down the drain and into the sewer. By contrast, modern low-flow showerheads use only 2.5 gallons per minute, or 12.5 gallons for a 5-minute shower, reducing water demand by at least 50%.
From [here](http://www.sahra.arizona.edu/programs/water_cons/home/bathroom_shower.htm).
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### Author:  [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)
#### Post date: [January 10, 2009, 5:59pm UTC](https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613/11 "2009-01-10T17:59:45Z")
Gray water contains the waste from the soap and other things used in it. Also it will contain bacteria washed off the bodies that used the water. Not sure I would want to use this water on a food garden.
When California was in a drought a number of years ago I turned the water off the toilets and water to flush the toilets. I kept buckets in the bathrooms to save the water.
When I would take a shower I would collect the cold water to flush the toilet. It took 2.2 gallons before hot water reached the bathroom. Hot water heater one cormer of garage shower farthest corner of house. I have since installed a circulating pump, instant hot water.
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### Author:  [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)
#### Post date: [January 10, 2009, 6:52pm UTC](https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613/12 "2009-01-10T18:52:15Z")
> [@NinetyWt](#):
>
> Might not take that long, depending on what kind of fixture used
Getting the water hot is not a function of the shower head, but the volume of cold water in the pipe that must be moved between the water heater and the shower, isn’t it?
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### Author:  [@NinetyWt](https://boards.straightdope.com/u/NinetyWt)
#### Post date: [January 10, 2009, 7:20pm UTC](https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613/13 "2009-01-10T19:20:55Z")
> [@carnivorousplant](#):
>
> Getting the water hot is not a function of the shower head, but the volume of cold water in the pipe that must be moved between the water heater and the shower, isn’t it?
You’re right. I don’t know what’s wrong with my reading comprehension this morning! Gah. What I was thinking is that it might not take long for five gallons to come thru the shower head, and if the shower were left running for 3 or 4 minutes it could conceivably fill a five-gallon bucket or two. I’m thinking also of my husband’s habit of turning it on “to let the water get warm” and leaving it running for five minutes or more. :dubious:
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### Author:  [@NoCoolUserName](https://boards.straightdope.com/u/NoCoolUserName)
#### Post date: [January 11, 2009, 5:07am UTC](https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613/14 "2009-01-11T05:07:59Z")
> [@Snnipe\_70E](#):
>
> Gray water contains the waste from the soap and other things used in it. Also it will contain bacteria washed off the bodies that used the water. Not sure I would want to use this water on a food garden.
Which is why I specified “flower garden watering” in the OP.
Altho’ I would be interested to know if there is any data re: the effect of soap residue on flowers.
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### Author:  [@NoCoolUserName](https://boards.straightdope.com/u/NoCoolUserName)
#### Post date: [January 11, 2009, 6:08am UTC](https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613/15 "2009-01-11T06:08:56Z")
> [@DMC](#):
>
> I would recommend you read [this](http://en.wikipedia.org/wiki/Greywater) before doing anything.
The Wikipedia article referenced specifically says:
> [@](#):
>
> Water recycling without purification is used in certain agricultural companies (e.g. tree nurseries, paprika producing companies) and dwellings for applications where potable water is not required (e.g. garden and land irrigation, toilet flushing).
I’m particularly intrigued by the “paprika producing” bit:). Anyone know what that is all about?
In any case, it sounds like using bath water for the flowers is really OK. Now I need the physical system parts.
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### Author:  [@Bridget\_Burke](https://boards.straightdope.com/u/Bridget_Burke)
#### Post date: [January 11, 2009, 2:25pm UTC](https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613/16 "2009-01-11T14:25:03Z")
I’m a renter; in Houston, that means that my landlady pays the water bill. A few years ago, we had a very dry spring; people were instructed to stop watering lawns. (Usually, there’s no shortage of rain coming up off the Gulf.)
So, most mornings, I left the bathtub plugged after the morning bath. When I got back from work, I used a giant plastic water can to dump cooled bathwater on the clumps of flowers & herbs I’d planted. They stayed alive!
Yes, I ate some of the herbs. Not while they were wet with bath water. I figured that a few days of Texas summer heat & a quick rinse after picking would protect me. I stayed alive, too!
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### Author:  [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)
#### Post date: [January 11, 2009, 3:07pm UTC](https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613/17 "2009-01-11T15:07:07Z")
I’ve wondered about draining the kitchen sink to a flower bed. Soap, compost from the disposal and hot water.
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### Author:  [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)
#### Post date: [January 11, 2009, 3:15pm UTC](https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613/18 "2009-01-11T15:15:51Z")
Some farms used to dump grey water the ground to save the septic system. The area where the water spread was not conducive to plant growth. That’s personal observation when I was a kid. The residues build up after a while, so don’t wonder later why the plants are not doing really nice like your neighbor’s.
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### Author:  [@Laughing\_Lagomorph](https://boards.straightdope.com/u/Laughing_Lagomorph)
#### Post date: [January 11, 2009, 3:24pm UTC](https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613/19 "2009-01-11T15:24:26Z")
Theoretically I suppose you could eliminate some of the concern about soap residue anyway by using biodegradeable soap.
Many houses in our town have had special wells drilled for non-potable water just for use in watering gardens and lawns. The high water table in the area makes this a viable option for people who are so inclined, after the initial investment the only cost is the electricity to run the pump.
(They also have to buy the signs that say “Private Well in Use” so people don’t try to turn them in for flouting the water conservation laws.)
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### Author:  [@Balthisar](https://boards.straightdope.com/u/Balthisar)
#### Post date: [January 12, 2009, 1:11pm UTC](https://boards.straightdope.com/t/using-gray-water-for-flower-garden-watering/480613/20 "2009-01-12T13:11:42Z")
> [@Laughing\_Lagomorph](#):
>
> Many houses in our town have had special wells drilled for non-potable water just for use in watering gardens and lawns. The high water table in the area makes this a viable option for people who are so inclined, after the initial investment the only cost is the electricity to run the pump.
I’ve been considering this option myself. Even with a deduct meter, my water bills are expensive during lawn-watering season, and I’ve still to add the back yard, which will more than double my existing irrigation water use.
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