Graywater is an excellent resource that we often don’t think about and just flush away down the sewer drain. One astute reader asked the following questions:
- Why can’t we just use the washing machine water to water the lawn?
- What is the graywater system doing for us?
- Does it filter the water? For what? Do the filters need to be changed?
- Why so expensive? We have already paid for the water, now we choose to reuse it…
What is the graywater system doing for us?
When you contemplate capturing rainwater or reusing graywater you are really contemplating becoming a mini-utility – a water resource and water treatment plant that, in a limited way, sources and treats its own water supply. In that capacity, you the homeowner have the responsibility to maintain a safe, consistent supply of water to meet the designated demand levels. It is meeting the demand where systems can be as simple as running the hose out of the slop sink onto the lawn to as large, complicated and expensive as a house wide containment system. It all depends on the goals you set.
The cost also depends on what stage of construction you are in. If you are building a new house, the cost of such a system can be built into the cost of the plumbing system for a smaller price premium than you can with a retrofit of an existing home. The base tank and filter costs may be the same but installation costs will be significantly less.
Goals Example 1: One goal could be to avoid sending washing machine water to the sewer or septic system just because it feels wrong to dispose of it when the plants would be perfectly happy AND its already paid for. Why waste good water? This simple system works well in the spring, summer and fall but not so much in winter because of freeze hazards. It saves lots of water and meets the goal. But it does not store water for a future need (drought) nor does it collect the volumes created in the off-season. That may be okay for some needs.
Goals Example 2: Another goal might be to supply water to toilets only but on a low budget. Domestic water and graywater must be piped separately. That means that once the decision is made to supply the toilets with graywater, they are disconnected from the domestic water supply and fed only with the graywater.
One way to do this is to calculate the volume of water that can be supplied from the various household sources and balance that with the needed supply to balance the system; avoiding any connection to the domestic system. Then a tank that held enough to meet the supply would be sized and the appropriate filtration systems would be designed. This tank could be quite large and take up a lot of expensive real estate as well as be expensive to purchase and install.
An alternate and less expensive option would be to install a smaller tank with the requisite filtration systems and install a back-flow valve protected domestic water make-up system that would automatically fill the tank if the graywater sources did not meet the needs of the toilet demand. In this case, domestic and graywater would commingle in the storage tank and the graywater piping would feed the fixture.
Goals Example 3: Yet another goal might be to optimize the tank size so that the graywater supply balanced the forecasted toilet and washing machine demand. This could result in the installation of a pretty hefty tank with domestic water make-up just in case.
Why can’t we just use the washing machine water to water the lawn?
We can use the washing machine water to water the lawn. I use it to water the gardens that are near my house. That water is a great resource for watering any outdoor plant if you use safe and gentle laundry soaps and no harsh chemicals or chlorine bleach in the wash. The ground will filter the soaps and the plants will thank you for the gallons of water delivered from a single load.
We had discussed capturing rainwater to meet the needs of the exterior landscape. That would allow using the graywater to exclusively meet interior needs.
Does it filter the water? For what? Do the filters need to be changed?
Graywater can be sourced from several different sources within the house – bathroom sinks, showers, tubs, and the washing machine. Because water from any of these places may contain solids: lint, hair, dirt, etc… the graywater system requires sediment filtration. This can be cartridge filtration or sand or some combination of the two. The filtration system should be inspected at least once a year and changed as needed. Because water from all of these places has the potential to contain fecal matter, all graywater systems must provide UV filtration. This is the case even if the water is destined to be toilet water. The UV filter light should be inspected at least once a year. The required filtration systems will bring the water almost up to potable standards.
Graywater can serve as supply for the washing machine and toilets so knowing that the water is filtered can bring peace of mind and significantly reduce the potential for contamination and spread of disease. That last is the governing goal of your local Health Department – avoid the occurrence and spread of disease.
Why so expensive? We have already paid for the water, now we choose to reuse it…
This last question opens up a huge debate, argument, discussion…about water in America. Water is really inexpensive here because we are resource rich and haven’t had to, maybe until now, search for or process substandard water and we do not bear the full burden of the cost to deliver it.
Slowly municipalities and water companies are awakening to the thought that the many of the existing water mains have to be maintained, fixed and maybe even replaced at enormous expense. Last year the American Water Works Association did a comprehensive study and report on America’s water infrastructure entitled “Buried No More: Confronting America’s Water Infrastructure Challenge” that details the scope and breadth of the problem we face.
The municipalities and water companies are also wrangling with the costs to treat the water going up as the quality of water deteriorates.
And in many areas of the country they are facing the reality of existing or looming shortages. In 2010, 24/7 Wall Street printed an article entitled, “The Ten Biggest American Cities That Are Running Out of Water”. This list included: San Francisco, Atlanta and Orlando. Not places you normally think of being water challenged let alone out of water.
I think that, as a people, we are at the very brink of understanding the seriousness of the issue and we are seeing an industry that is pretty mature in places like Australia, coming in as a new technology here. I think that prices will moderate with time as the populace accepts the idea. I also think that it is very important that the government mandate the use of rainwater catchment and graywater reuse systems to meet current and future needs and to push market acceptance forward.
