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Reuse Your Bath Water! It’s a Win-Win

Greywater from the bath can be used to water the garden

Wondering how to reuse your bath water? It’s worth figuring out. Why? Because when you reuse your bathwater, you create a win-win for your pocketbook and the earth.

Reuse bath water by manually moving it to a garden, toilet tank or water. Or you can configure your pipes to use gravity or an air pump to move gently used bath water to a desired location for reuse. However, the most high-tech way to reuse bath water is to install a separate tank designed to clean impurities before reuse.

All of these methods, from the least expensive to the most expensive, will save you money on your water bill. You could potentially save thousands of dollars a year while reducing your environmental footprint.

So, with that in mind, here’s how to reuse bath water, beginning with low-tech methods and ending with the highest-tech method:

SystemLevel of TechnologyHow It WorksCost
BucketManualScoop out tub water and move to toilet tank, garden, etc$
Pond PumpLowAttach to garden hose, through window, to tub$$
Gravity BasedMediumInsert diverter valve in pipeline$$$
Air Pump in PipelineMediumInsert diverter valve and air pump in pipeline$$$$
Greywater TankHighDrains tub water into separate tank. Then filters, treats and divers water for reuse.$$$$$

And if you’re looking to really create an energy-efficient bathroom, be sure to read 16 Tips to Make a Bathroom Energy Efficient (& Save Money!).

How to Reuse Bath Water: Low-Tech Systems

Gently used household water is called gray water. Here are two easy, low-tech ways to move gray water from your tub to another location for reuse:

The Bucket

5 Ways to Reuse Bath Water

Some people keep a bucket next to the bathtub. When a bath is finished, they use the water to fill the toilet over the course of the week. Or some hardy souls lug the bucket to the garden. I use the bucket method on occasion. It makes me feel great to water the plants or wash the car with my leftover bathwater.

I especially recommend encouraging children to reuse their bathwater. It helps them feel empowered that although they are small, they can do big things to help the earth. Here are 5 ways to reuse bathwater that you collect in a bucket:

1. Water Indoor Plants with Tub Water

Take a bucket or two of bathwater and use it on your plants! Better yet, invite young children to participate. This can be an easy and effective activity to teach them about recycling, and it only takes a few minutes. 

2. Wash Your Car with Water from the Tub

Take a few buckets out to the driveway and dump them on your car. You’ll not only save the expense of going to the car wash, if you make a habit of this, your car is likely to look pretty spiffy.

3. Pour Used Bath Water into the Toilet Tank

Some people claim to get 30 flushes out of recycling 30 gallons from of a single bath. That could take care of flushing for your whole family for several days. The added benefit? There usually isn’t too far to take the bathwater. And if you get clever you may able to hook up a pump system so there won’t be any manual labor involved. Just be sure to recycle the used tub water directly into the bowl and not into the tank.

You can also save water by purchasing an eco-friendly toilet. Read my post, 9 Best Toilets to Save Water in 2022 to learn how you can save water in your bathroom.

Also read my post, Water-Saving Toilets: How Much Will You Save? to learn how much water (and money) you will save with a water-saving toilet. 

4. Bathe Pets with Recycled Bath Water

Once your sweaty kids have finished their baths, why not reuse the water for your pets? I doubt Fido will notice or care that the water has already been used. And he’s been smelling a bit lately, right?

5. Water Your Garden

It might be easier to haul bath water to indoor plants, but when you think about how much water is in a tub, you’ve got plenty to water your garden as well. You don’t have to do it all at once. Fill your watering can throughout the day, take your time walking in and outdoors, and enjoy knowing what a good friend of the earth you are.

Reuse Bath Water with a Pump

Bathtub to Garden Easy Low Cost DIY Graywater Recycling to Your Plants

Another way to remove your bathwater that is slightly less manual than a bucket is by using a pond pump like this one. Attach a garden hose or drip system tube to the pump. After the bath, simply immerse the pump in your tub water and place the hose out the window. Many pond pumps can empty 30 gallons—a typical bath—in one minute.

To keep your garden healthy, don’t always pump grey water to the same place in your yard. And you might want to let the bathwater cool down before putting it onto your plants.

That looks easy enough! But what if you don’t want the hassle? You’re too busy to brush your teeth, let alone try the pump-to-garden system. What are more automated options for getting bathwater to the yard?

Reuse Bath Water: Medium-Tech Options

Branched pipe for a grey water system

An organization out of California called Greywater Action has a super-helpful website. Greywater Action provides educational workshops and advice about installing water recycling systems. These systems can restructure your pipes to divert water from your garden after you bathe.

How to Reuse Bath Water with a Gravity-Based System

This system involves installing a diverter valve in your pipeline that will funnel grey water from the bathtub into multiple irrigation pipes that lead to your garden. The water flows downhill through the pipes. However, if your garden is located uphill from your home, you won’t be able to use this system.

How to Reuse Bath Water with a Pump System 

This will be more expensive to install than a gravity-based grey water system. While you will still place a diverter valve on the drain water, you’ll also need an air pump to redirect the flow since gravity is not on your side.

To DIY the installation of these systems, consult Greywater Action for details. And be sure to check out this example of one Branched Drain System. Keep in mind it can be difficult to locate the correct pipes if they are buried deep in the walls. Expect to pay $150-$300 for parts. If you want to pay for installation, rates probably start at $1,000. 

Also, an important note: To avoid clogged pipes, use pipes that are 1.5 to 2 inches in diameter, and don’t use pipes with U-bends.

How to Reuse Bath Water: High Tech System

Greywater Systems | Aqua2use Greywater Diversion Device

The most sophisticated systems involve installing a separate grey water tank. This system filters the water that comes into the tank to get rid of lint, hair, and other impurities. It can save a family of four up to 40,000 gallons of water a year.

One company that sells grey water recycling tanks is called the Water Wise Group. It’s a wholesale distributor of greywater systems. Headquartered in Templeton, California, the Water Wise Group ships around the country. Owner Remy Sabiani told me:

Our systems can recycle greywater coming from the bathtub. The main benefit is to reuse the water to water your plants, trees, and flowers. You pay for the water once, and you use it twice!

Remy told me that most clients use the Aqua2use GWDD. Pricing is $699 per unit. He recommends working with a plumber to set up and connect the system, which will usually take 2-3 hours.  

Shampoos and Soaps to Use in Grey Water

Wait just a minute! I hear you say. What about the soap and other debris like hair or shampoo residue that might be in that water? That could kill my plants! 

Well, you’ve got a point. So, what soaps and shampoos are safe to use for grey water? Let’s investigate.

According to Greywater Action, there are a few main rules to follow when using grey water in the environment:

  • Send nothing toxic down the drain.
  • Do not allow grey water to enter a freshwater source, like a creek, stream, or river, or high groundwater table.
  • Use biodegradable products that are salt and boron free.

Laura Allen is a founding member of Greywater Action and the author of The Water Wise Home: How to Conserve, Capture and Reuse Water in Your Home and Landscape. She specifically recommends the following brands for soaps and shampoos: Aubrey Organics (most types), Everyday Shea and Dr. Bronner’s.

For a complete list of ingredients to avoid in shampoos and conditioners, be sure to take a look at the Red List from the Campaign for Safe Cosmetics.  

Contaminants in Recycled Bathwater

Grey water usually contains bacteria that washes off our bodies, as well as chemicals from the products we use.

And if you really want to know…and you may want to stop reading here…there will be some fecal matter found in bath and shower water. But research finds that this is actually no problem for your plants. In fact, you might want to think of it as free fertilizer. Really!

A study found no increased health risk from consuming plants watered with tap water vs. grey water. (Some questions remain about using grey water to water root vegetables that will be consumed raw.) And other studies find that your carrots and tomatoes might even shoot up higher than ever when watered with grey water instead of tap water. Go figure!

And while legal to install a grey water recycling system in many states, be sure to check out the laws where you live before investing time and money. In some states, you’re required to reuse water within 24 hours if it’s not treated.  

Baths and the Environment

If you’re thinking about the impact of your bath on the environment, you might want to calculate your own Bath vs. Shower footprint. While you may think you know which is better for the environment, your own personal bath vs. shower result may surprise you.

And since you’re an earth-lover, we can assume you’d love a little nature indoors. Did you know that there are many plants that will thrive in your bathroom and purify the air at the same time. Check out our post on the 23 Best Bathroom Plants. Just imagine how you can water them with your reused bathwater!

Related Questions:

Can you reuse bath water after 24 hours?

If you want to use bath water after 24 hours, you should treat it to prevent bacterial growth. Untreated, gently used bath water can also start to smell due to diminishing oxygenation of the water.

Can you reuse hot tub water?

Yes, you can but you need to ensure the chlorine level is zero and that it is legal to do so where you live. Many hot tubs or jacuzzi’s hold 650 gallons, so diverting that water to the yard would be great. Don’t add chlorine to the water for two days prior to draining the hot tub, and then test the chlorine level to ensure it’s at zero. If it’s not, run the hot tub for a few hours and test again.

Tags: Aqua2use, Aubrey Organics, Campaign for Safe Cosmetics, Dr. Bronner's, Everyday Shea, gravity-based grey water system, gray water, graywater, grey water, greywater, greywater action, Laura Allen, pump grey-water system, Red List, reuse bath water, reuse tub water, The Water Wise Home, Water Wise Group

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