Here are some basic tips for best use of your greywater system during a drought or under regular conditions:
- Regularly check your greywater system to be sure it is functioning properly.
- Keep an eye (and a nose) out for leaks.
- Operate your greywater irrigation system efficiently to provide sufficient water to your plants while minimizing loss from deep percolation beyond the root zone.
- Clean and/or replace your graywater filter regularly.
- Frequently check your plants that are greywater irrigated for signs of over watering or stress from high organic content in the water.
- Check for information about ingredients in laundry products that may affect the plants you are irrigating.
- Publicize your successful greywater system and encourage others to adopt the technology.
During a drought, a greywater reuse system could be an excellent way to maximize water use efficiency in your home and keep precious plants and trees alive. Although other drought actions taken inside the home (such as reduced showering) could reduce greywater flows a little, the greywater will still be a valuable resource. During a severe drought, your neighbors will be envious of your thriving greywater-fed landscape as their lawn and shrubs wither and turn brown for lack of water.
Greywater and/or Dual Plumbing System Water Savings
Using greywater for irrigation so that regular tap water need not be used is an excellent way to save water. The amount of greywater captured and available for irrigation is a function of the greywater system itself and how much water is used indoors.
Simple greywater systems that utilize a bucket in the sink and shower or a hose hooked to the bathtub drain can save a maximum of the capacity of the bucket or bathtub each time it is filled. A carefully designed greywater system that is connected to sinks, tubs, showers, and the clothes washer can create approximately 35 gallons per capita per day or 12,775 gallons per capita per year. A family of four could potentially create an additional 50,000 gallons for use outdoors. This of course assumes that the system works perfectly, all possible fixtures are connected to the system, there is sufficient storage, and very little water is lost in the filtration process.
More realistically, a family of four with a well designed greywater system with nearly all potential fixtures connected could save 30,000 to 40,000 gallons of water per year and in many cases it may be less than this.
Benefits and Costs
The cost of a greywater system depends upon the size and scope. The most basic greywater systems involve only a bucket or basin and perhaps a garden hose while elaborate systems require water from sinks, bathtubs, showers, and clothes washers to be piped into a storage tank then pumped into an irrigation system.
The maximum average expected water savings from any greywater system is about 50,000 gallons per year for a family of 4. Assuming a relatively high water cost of $3.00 per thousand gallons, this amounts to a savings of about $150 per year. With a maximum savings of $150 per year, it is difficult to design a truly cost effective greywater system.
According to one of the leading greywater web sites, the huge majority of “successful” (i.e., cost effective) greywater systems are so simple as to not be noticed by regulators, manufacturers, consultants and salespeople.
Simple and basic greywater systems are far more likely to be cost effective than expensive packaged systems or even custom designed systems.
Substituting greywater for regular tap water to irrigate can help reduce household water and wastewater use, which can have far reaching environmental benefits. Water conservation reduces water demand, which allows rivers and streams to maintain adequate water levels and flow. This helps to sustain healthy aquatic ecosystems. Conservation also reduces the need to develop new water treatment facilities and new water storage – a process that often causes unfavorable environmental repercussions. Additionally, conservation reduces the need to overdraw from groundwater resources, which can be vulnerable to depletion and contamination. Indirectly, saving water also helps to reduce energy consumption for water and wastewater development, treatment, and distribution.
Macro vs. Micro
The future of greywater and reuse systems may be more in larger utility sponsored systems rather than in small-scale residential systems. Many utilities are actively pursuing the option of collecting, treating, and reusing graywater and delivering this water to customers via a dual pipe network. This water is primarily used for irrigation at larger sites such as schools, parks, and office buildings.
On the other hand, small-scale greywater systems installed at individual homes have had mixed success. Some systems perform well and give years of service while others are abandoned after only a short period of time. Development of residential greywater systems is complicated by the fact that small greywater systems are not legal in some cities and states. This can quickly stifle efforts to market and sell this technology. Furthermore, economic analysis of the potential water savings, benefits, and system costs reveals that these small systems are unlikely to be cost effective.
Unless local laws are changed and the price of water increases dramatically, it is unlikely that small-scale residential greywater systems will reach a mass market in the near future.