Graywater systems are efficient

Ask the ExpertsWith all the development impacting our local water supply, how can we feel more secure about drinking the water in our homes?
There is no question that the impact of development, growth, and expanded tourism weighs heavily on the availability of sufficient drinking water from Loreto on down to the tip of Baja. Local citizens, elected officials, and government agencies have become increasingly engaged in discussions with experts from all over the world to explore the best solutions to our potable water challenges. Studies focused on the next 10-25 years have been conducted by experts from Harvard University, University of Arizona, UABCS, San Diego State University, CIBNOR, and Scripps Institute of Oceanography, among others. Desalination emerged as a key predicator for future population growth, but so many other factors enter into the mix. It would take up this entire Newsletter to get into the politics surrounding the pros and cons of potential solutions. There is no question that future large-scale resort developments have a responsibility to provide their own potable water systems, and for the moment we can only guess how local population growth will impact our marine and terrestrial eco systems and water tables.

That said, there are differences in the challenges between big towns and rural areas as well. There is only an average of 8″ of yearly rainfall in Baja, and the water supply for most of our southern Baja larger communities comes from the aquifers from our local mountains, such as the Sierra de la Laguna range. The water is very pure. It’s the pipes used to distribute the water that cause problems. In more rural areas, people depend on wells for their drinking water, which unfortunately, often show contamination due to exposure to agricultural and animal transmissions. So while the experts and legislators are figuring out what’s best, and working out how our potable water gets supplied and treated, what can WE do in our homes?

Graywater Regulations
When discussing graywater use regulations, an important distinction is whether graywater application is surface or subsurface. In the States, the water quality standards for surface irrigation are more stringent than what is required for subsurface use, defined as the area below the surface level. Subsurface use must meet water quality standards for groundwater.
use. Distributing graywater below two feet greatly limits its usefulness. Some critics claim it totally negates its usefulness. The definition of subsurface is defined according to soil types. Minimal subsurface depth for sandy soils is eight inches, with a greater depth set for clay soils, between about ten and 12 inches. Some critics claim that by defining surface area as two feet below the surface, as in Arizona, the rules essentially intend that all graywater use will be surface
No single understanding of the benefits and hazards of graywater use guides policy makers. Drought prompted California to graywater use. Graywater applied to the landscape saved both potable water as well as the landscape, which led to legislation to adopt standards for the installation of graywater systems and the use of graywater. In California, an approved subsurface drip irrigation system must have a surge tank of between 50 to 100 gallons to collect the graywater. When it reaches a certain level, the water is pumped from the tank through the drip irrigation system. Filtration is required for graywater use in drip irrigation systems. As you will read below, though, drip irrigation is not a great way to go. With a mini-leachfield irrigation system, a surge tank is not required. The graywater flows directly into the leachfield.
GraywaterStoring Graywater Storing
Storage rapidly turns graywater into blackwater. The word “storage” should immediately sound an alarm, as should anything that includes a tank bigger than 55 gallons, for residential systems. If you doubt this, just fill a bucket with graywater and observe it as it progressively darkens and becomes more fetid. Bacteria multiply to blackwater levels as well. In Mexico the trampa de grasa (grease trap) often included in graywater systems is a very popular way to commit this mistake…omitting or bypassing the trampa de grasa would be much better.

Twenty four hours is generally considered the prudent maximum time for storage. Since this is not enough time to store graywater from a time when irrigation is not needed to one in which it is, it’s best to just send it all straight to the soil.
Manually distributed graywater can be stored for the day to allow for manual distribution all in one session. Tanks for this purpose should be designed to drain COMPLETELY (to not leave a bit of fetid graywater at the bottom to affect the next batch) and NOT BE TOO BIG as this invites misuse in the form of letting the water sit too long.

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