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Saving Money by Creating Your Own Greywater System

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Being green is not just about energy; lowering your water usage by using greywater from your home is also eco-friendly.

I first became aware of the concept of water conservation when I was staying with relatives in Berlin over thirty years ago, and it all started with a bath. Tante Magda informed me not to be wasteful by filling up the tub to the brim with water; I was only supposed to have a few inches of water in the tub to bathe in. From there, a friend pointed out different ways in which rain water was being collected and used in the buildings. It had never occurred to me that we would need to conserve water.

When I call my father, one part of our conversation frequently turns towards Canyon Lake. He lives as close as one can to this man-made body of water. The dam was built in part to prevent flooding down river, but it also serves as a water source for the area. The Edwards Aquifer has not been able to handle the growing population of the hill country, so San Antonio has tapped into Canyon Lake to help meet demand. As these water sources become more precious, we begin to realize how wasteful we have been.

Installing smarter water systems in our home can be a solution. In this post, I want to introduce you to some of the concepts of saving water in your own home by focusing on greywater, but touching upon other types of water around your home.


Rainwater: pretty self explanatory- water coming from the rain. Collecting water through a gutter system from all of your roof surfaces into storage barrels is the main way to use this water. However, you should also consider the topography of your site. Slowing water’s progress away from your home, so it can be used by the plants is also an aspect of using rainwater.

Blackwater: this is water from toilets (contaminated water with feces). There is a common misconception that you cannot reuse blackwater. The technology has existed for some time of cleaning this water to be reused. Many bog plants, like cattails, have the ability to purify water. The problem for the homeowner is such systems are not practical for most residential applications. Here is a good infographic on this system.

Greywater: this is water which has been used or produced in your home which is not blackwater. Most of you familiar with the concept of greywater will think of it as water which has been used in washing (laundry, hands, dishes, or body). If you have a forced air system to cool your house, you will have an evaporator coil. This coil is cooled with a refrigerant. The air forced over it is cooled by the coils. The moisture in the air condenses on the coils, and it is removed from the home by the primary drain line. If you have dehumidifiers, you will also obtain water from air moisture with those units.

A note of caution should be inserted here before I go further. Many states west of the Mississippi have laws which regulate water rights in a fairly strict fashion. I know that there will be readers from outside of Houston, so I want to suggest before you install a rainwater or greywater system, check with your local building apartment to see if it is legal. As far as I know, Texas has no rules against such systems. In fact, rainwater collecting has been standard in Texas. I asked other home inspectors around the state if there were local regulations, and I was told that they knew of none.

Another concern about greywater is what might be in the water. This really is a concern when planning out how this water will be used. Dishwashing and laundry detergents can be harmful to plants. There are many eco-friendly detergents, and you may wish to use them if using wash water for your garden. The soap used for washing your hands,hair, or body may pose a problem, but it is not as great a concern, so you could use it without much worry. If you use your food disposer often, this may also be a problem. Waste from cooking is better handled outside of your waste waste system. Grease, ground food, or other solid can clog pipes, as well as encouraging a pest problem when used in garden beds.

Where to obtain greywater from your home

Air conditioning: the primary drain line for your evaporator coil can drain water away in two ways. In older homes, the pipe comes out of the coil and runs out of the attic through a wall to drain to the exterior. In newer homes, you will find a black hose attached to a drain for a bathroom sink. A few homes may have dehumidifiers installed in the line of the air flow. Their lines follow the pattern of the evaporator coil drain. You have to check your bathroom sinks for a black hose installed before the p-trap. If you do not find one, then your drain is going to the exterior. Following the line in the attic can help you determine where it is. To identify your evaporator coil: it is a rectangular box after your heater and it has a safety pan underneath it. It also has two copper lines coming from the compressor outside into it.

Sinks: water drains from your sink through a tailpipe which leads to a pipe that has a shape similar to the letter p (this is the p-trap). This trap collects water to stop sewer gases from coming back into the home. Collecting water from a sink is fairly easy for a homeowner to setup if you are thinking of doing it yourself. You will need to cap off the waste line to prevent those sewer gases coming into your home. Set up your piping after the p-trap.

Dishwasher: this has a drain line which goes into the kitchen sink drain. If you look at the drainage pipes for this sink, you will see a flexible tube coming from the cabinet with the dishwasher. You could collect this water along with the sink water, or you could disconnect this hose to use it separately from the sink water. Be sure to cap the connector on the drain pipe where the tube was removed.

Clothes washer: this has a hose coming from the back of the unit to a drain tube in the wall behind it. Typically, the hot and cold water taps for the washer are set in a box with the drain. You would just have to remove the washer hose from the drain to divert this water from use. I would place a cap on this drain to prevent sewer gases from entering the home.

Tub and Shower: the shower’s drain may be quite difficult to access, but there is no reason why its water cannot be used. A first floor shower has its drain in the slab, so everything will have to be dug out (shower enclosure and foundation to exterior) Tubs may be easier, but still requires some work to access. Many tubs have access panels (or one can be created). The foundation under the tub will likely already be open, so you will need to create a hole in the foundation wall from the exterior to the tub opening for a drain line.

Where can you use greywater

The first place (and frequently the only place) homeowners use greywater is in the garden. You can feed this waste water into a drip system or to an underground watering system for best results. Spraying this water on leaves may hurt the plant. This involves running the pipes along your garden beds so that the discharge water flows to all its parts. You can create a storage system where water from the bathroom sink will be used for the toilet. This involves forcing the water from the drain up to a tank for the toilet. You may also want a storage tank to use this water for washing your car or home. There has been talk of cleaning greywater to be reused, but this system would be much more costly to install and maintain.

Is this a do it yourself project?

I would have these conditions in mind if you are thinking about doing it yourself: easy access to the drain (which rules out tub and shower); the ability to work with pvc and cutting holes through exterior walls; and is the wall an exterior one. If these conditions are met, I believe setting up a greywater system for your garden as a weekend project is within the capabilities of many people. Gluing pvc is not hard, and cutting a small hole with a drill saw is not hard. If you have brick or masonry, you would have to chisel out the brick, and then refill that space to look good. When setting up sink water for the toilet or storage devices for other uses, you will want a plumber to do it right. Gaining that water from the tub and shower will be the real expense if you wish to go that far.

A final thought

If you are adamant about being green, or you are concerned with saving money over time, I would give consideration to using water for your toilets or in storage tanks for the car or exterior house cleaning. How much money will you save? Since I have been working towards reducing my water usage, I could see my savings being possibly $10 to $15 a month at most (my current bill averaging $50 a month). It all adds up, but you may not see huge savings. If you are using four times the water that I am, your saving may be much more. Also, you may find savings by an extra means. If you look at your water bill, you will see that the cost includes water coming in and out of the home. The water out will be more than water in. This happens because your city may include trash pick up costs in the water out charge, but it may also include water from rain. I one time knew a man who had the city install a meter to measure his waste water to reduce his bill. If you are reusing the water, then should the city charge you for it? Contact your city’s water department to see if they have a way to measure your waste water, or if they give a credit for rainwater/greywater systems. You never know.

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5 Responses to “Saving Money by Creating Your Own Greywater System”

  1. JT Says:

    Does this City of Houston Allow Grey water systems?

  2. I have found nothing against it, and I have seen grey water systems installed.
    Update: I did find that the City of Houston does have some restrictions on how a grey water system is set up. The building resource department should be able to help.

  3. […] ways to work on limiting water usage at home: How to create a rain water collection at home Re-using greywater Water saving devices Xeriscape in Texas or other South western states Use only water friendly, […]

  4. Andrew Says:


    I just wanted to let ya’ll know about this great new website – http://www.cleanwatercomponents.com. It has diagrams and greywater system design quidelines for the most popular graywater systems out there and they also sell all the products you need for these systems. I’m especially excited about that last bit – I’m tired of tracking down the parts for these systems from 3-5 different vendors.

    Thanks Clean Water Components!

  5. Hello Andrew,

    it is a good site. I like the education section. I especially like the fact that the site includes rainwater as well. People should check it out.

© Frank Schulte-Ladbeck Professional Home Inspector Houston, Texas
Frank Theodor Schulte-Ladbeck
home inspector, TREC# 9073
Houston , Texas , 77063 United States

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