Reducing Waste, Using Graywater

ADVERTISEMENT

Saving Two Ways

A hundred years ago, clean water for drinking and washing was uncertain in all but the most settled areas; now we take it for granted everywhere. But at current rates of consumption, we use 500 billion gallons of fresh water every day in the United States. The problem with our water supply is no longer whether it’s safe, but whether it will continue to be available.

A Definition of Graywater
 
As it is commonly understood, graywater is used water from sinks, showers, bathtubs, and washing machines. It does not include water from dishwashers, or from any fixture that washes away human waste. Usually, that just means toilets, but it can include washing
machines that are used to clean soiled diapers. For lack of a better term, this kind of waste is known as blackwater. Whether kitchen sinks produce graywater depends on the definition currently held by your local building codes; if in doubt, assume it’s not safe to use.

In most households, more than half of the water used results in graywater waste. If that much can be diverted for landscaping and

other uses, it can represent large savings over using additional fresh water for the same purposes.

Basic Requirements

Unlike low-flow fixtures, which only require you to remove an existing plumbing part and thread another in its place, graywater collection depends on a completely new, separate set of drain lines. To divide your blackwater drains from those that carry graywater, you will need to undertake extensive plumbing work. If you’re not confident in your abilities as a plumber, consider hiring a professional contractor. And whether you hire out the work or do it yourself, make sure you check all building code rules and get approval from an inspector before you begin.

New houses are much easier to fit for graywater collection, because they don’t have drain lines in place yet. Everything starts from scratch. In houses that have already been completed, retrofitting is possible within limits. An older house with a concrete basement
floor is especially difficult to retrofit. In such a case, only the washing machine could be fitted for graywater collection.

How Graywater Is Collected and Used

The simplest form of graywater reuse is emptying the remains from a pet’s water dish into a potted plant before you refill the dish. If you think about it, an integrated whole-house graywater collection system connected to an automated landscape watering setup is really
doing the same thing, just on a larger scale.

Determined recyclers have developed ways to collect graywater from bathtubs and washing machines, but these methods involve still more work. Carrying a gallon bucket outdoors and pouring it on the garden is little effort compared to draining a tub or washer and
hauling the contents somewhere else by hand. Even the people who practice this method call it tedious and backbreaking.

If you’re like most people, collecting the waste water from air conditioners, dehumidifiers, and other appliances seems like more trouble than it’s worth. So, if graywater collection makes economic and ecological sense, you’ll probably want a passive system that doesn’t require constant attention.

In a system like that, new drain lines are installed, and the waste water from sinks, showers, bathtubs, and washing machines runs into a storage tank. Water from the tank can be pumped out by hand or with a mechanical pump. Because most health and safety rules only permit graywater to be used for landscape irrigation, it is generally routed to a drip-watering system. Spraying is usually not allowed. Professionally installed systems can include automatic valves that redirect the flow to the sewer if the storage tank is full.

Economic and Environmental Benefits

In parts of the country that regularly receive plenty of rainwater, such as the Pacific Northwest, graywater collection may not make as much economic sense. It still reduces the amount of fresh water consumed and waste water that flows into municipal treatment facilities. But in dry places, like the Southwest, water rationing is already a fact of life, even as landscaping represents a higher proportion of residential water use. Where water is scarce, saving water is more valuable.

By some estimates, the average American household uses up to 15 percent of its fresh water consumption to sustain plants. Nationwide, that could add up to savings of more than 6 billion gallons of water every day. Add the water used for landscaping, factor in the savings in processing of both fresh water and waste water, and the potential difference is significant.


Using Graywater—or Not

The Arizona Department of Environmental Quality provides helpful information on collecting and using graywater. Advice from the department includes the following tips:

Do:

• Filter your graywater with something as simple as a stocking to trap hair and lint.
• Frequently check your plants for evidence of overwatering or damage from organic material in graywater.
• Use graywater only for flood or drip irrigation.
• Divert graywater to your sewer or septic system if you are laundering diapers or dyeing clothes. 
• Structure your irrigation system so it doesn’t waste water by letting it percolate beyond the root zone.
• Use PVC or ABS piping.

Don’t:

• Drink your graywater.
• Reuse water that contains hazardous chemicals from photo labs, car parts, or oily rags.
• Allow your graywater to pond because it can increase health risks and provide breeding grounds for mosquitoes.
• Reuse graywater for spray irrigation.
• Irrigate root or leaf crops (such as carrots or lettuce) that you’ll eat.
• Reuse graywater if family members suffer from infectious diseases, such as diarrhea, hepatitis, or internal parasites.