In the average American home, about half of the water is used indoors, and the other half is used outside. A greywater system helps you reduce water usage. Many plants are perfectly happy with gently used water, and it can mean big savings for you, as well as an environmentally friendly solution to irrigation.
“Greywater” is gently used water from bathtubs, laundry, and showers. With many households facing drought conditions today, any measures taken to reduce water use is a step in the right direction. While it might have small amounts of lint or food in it, for the most part, greywater is a cost-effective solution to helping water your plants.
Elements of a Greywater System
Every greywater system will have some common components. Many use wood mulch. The bed of woodchip mulch filters large flows and contains them. It gives the spreading water capillary action. Another part of the greywater systems is the diverter valve. It will let you turn the greywater system off. This would be useful if your plants are getting too much water, or if you’re putting something down the drain that might be harmful to the soil. It lets you send the greywater back to the sewer if you need to. A third part of a greywater system is the subsurface emitters. Because you can’t use a sprinkler system, this is the solution. It’s distributed either underground or on the ground, and it is covered with mulch.
Here are the three simple steps to setting up a greywater system:
1. Reroute drainage to the greywater system instead of the sewer
2. Install the greywater system
3. Install outdoor irrigation
Just kidding, of course. Installing a greywater system is going to be more involved as you get into the details. Continue reading for some important considerations to take to heart when planning your greywater system installation.
A typical standard, top-loading washing machine uses 41 gallons of water per load. You can reduce this by installing a high-efficiency washing machine, but you can reduce it even further by reusing the water that would otherwise just go down the drain.
Laundry-to-landscape greywater systems route the drainage from the laundry into the greywater system, usually into an outside mulch bed. This system uses the washing machine’s discharge pump to move water out to the yard, allowing for the water to be pushed slightly uphill if necessary. Because water is typically drained through a flexible hose, maintenance is typically easier with this type of system. It’s also easier to switch back to the sewer/septic system if necessary.
Branched Drain System
Branched drain systems, as you might expect, branch the flow of the drainage from sinks, showers, etc., to multiple areas. They can be used in combination with laundry-to-landscape systems, and can combine multiple sources of greywater to be distributed across a yard.
Branched drain systems are generally gravity-driven, so the water must flow downhill to the destination area. It’s best to prepare the areas to be watered with mulch, which can help wick up and slow the flow of the water.
Sump Pump Systems
A sump pump pumps greywater from a collection basin into the rest of the greywater system. Sump pumps are a good solution for pushing greywater up hills or to distant areas. Sump pump solutions are typically operated by a float switch, which activates when the basin fills to a sufficient level, pumping the water out to the yard.
In situations where several zones would be connected to an irrigation system, there are more robust proprietary solutions available. These systems have electronic controllers and timers capable of efficiently watering sections of a yard on a schedule, thus minimizing waste. Some systems can detect rainfall and will not only disable watering but also backflush and clean the filters.
Things to Know about Greywater Systems
When planning your greywater system, keep in mind the change in elevation. Some greywater systems can only water downhill, and even with a pump, other systems can only push water so high.
Also remember to use detergents that won’t cause harm to vegetation. Detergents that contain too much phosphorus or sodium can kill plants. Also, be sure not to apply greywater to fruits or other parts of a plant intended for consumption. Greywater is not safe for consumption, and should not come into contact with foodstuffs.
Be mindful when planning on using a tank to store greywater. The organic material in greywater will cause bacterial growth, which can result in a foul odor. Routing the greywater directly into the soil/mulch instead of to a tank can prevent anaerobic bacteria from growing, which would prevent the odor.
When undergoing a DIY greywater project, it’s best to keep your design simple. With more complexity comes an increase in points of failure, which means more time spent maintaining the system. If you can, instead of installing pumps, use a gravity-powered system. This would also have the added benefit of reducing energy usage and decreasing your carbon footprint. If you feel like you’re getting in over your head, your local environmentally conscious plumber or handyman should to be able to help you out.