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How to Craft the Best Greywater Rules for New Mexico

Testimony by Art Ludwig before the
New Mexico State Legislature Water and Natural Resources Committee
September 5, 2002
Ruidoso Convention Center, 111 Sierra Blanca Drive
Ruidoso, New Mexico

Definition of greywater

I define "greywater" as all household wastewater other than toilet water.

A "greywater system" is any system that handles greywater separately from toilet water.

A typical greywater system collects washwater from bathing and laundry and guides it to the yard for irrigation.

Benefits of reusing greywater

You can do more with less fresh water

Greywater can replace fresh water for many uses, saving money, and increasing the effective water supply.

Residential water use is almost evenly split between indoor and outdoor. All except toilet water could be recycled outdoors, achieving the same result with significantly less fresh water supply.

Less strain on septic tank or treatment plant

Greywater use greatly extends the useful life and capacity of septic systems. For municipal treatment systems, decreased wastewater flow means higher treatment effectiveness and lower operation and capital costs.

Highly effective purification

Greywater is purified to a spectacularly high degree in the upper, most biologically active region of the soil. This protects the quality of natural surface and ground waters. In areas where groundwater is threatened with nitrate contamination from on-site systems, greywater reuse can help reduce this threat.

Improvement in on-site treatment performance at problem sites

For sites with slow soil percolation or other problems, a greywater system can be a partial or complete substitute for a very costly, over-engineered system. For sites with slow soil percolation, fast percolation or other problems, a greywater system can decrease strain on critical blackwater treatment facilities..

Less energy and chemical use

Less energy and chemicals are used due to the reduced amount of both fresh water and wastewater that needs pumping and treatment. Individuals reusing water are less likely to dump toxic chemicals down the drain.

Why New Mexico should revise their greywater law

The current law essentially calls for another septic system.

Ideally, building codes provide useful guidance. The current greywater law is not reasonable. Homeowners are dismissing it as a source of guidance.

The illegality of simple, reasonable systems stops only one group of people from installing them: Building professionals, who have their licenses to worry about.

A hundred thousand homeowners each making one system in isolation will not learn much. If greywater laws were friendlier, each building professional would install many systems. Professionals would build experience, share it, and make innovations.

Conditions in New Mexico are uniquely favorable right now for crafting a superior greywater law

FIRST, general regulatory trends around the nation are going this direction.

SECOND, health risk, the only objection to greywater reuse, has proven to be a non-issue in practice.

THIRD, greywater systems are already widely used in New Mexico.

FOURTH, you are in a drought emergency, exacerbated by reductions in water supply.

If you act to increase the usefulness of the water you have, the public will get behind this action as justified, visionary, and positive.

FINALLY, Arizona, your next door neighbor, has done you the favor of providing excellent political cover.

They've stuck their necks out farther than anyone else’s with their new greywater regulations.

It's a visionary law, and provides New Mexico an excellent template to follow.

Improving greywater laws could save water, improve water treatment, and enable building professionals to add an important extension to their work.

Specific suggestions for how to craft a superior greywater law for New Mexico

I suggest you generally follow the AZ greywater regulatory model, with a few improvements.

This will be less work and easy to justify.

They take a three tiered approach to scrutinizing greywater systems:

Systems for less than 400 gallons per day that meet a list of reasonable requirements do not require a permit.

With this one stroke, Arizona has raised their compliance rate from near zero to perhaps 50%.

And, homeowners are more likely to work towards compliance for the informal systems that still fall short.

What's more, the door is now open for professionals to install simple systems.

Second tier systems, are ones that process over 400 gallons a day, or don't meet the list of requirements, as well as commercial, multi-family, and institutional systems. They require a standard permit.

Third tier systems are over 3000 gallons a day. Regulators consider each of them on an individual basis.

In Arizona, regulators apply oversight to greywater systems in rational proportion to their possible impacts.

Another wise feature of the AZ law: ... It does not proscribe design specifics.

Instead, regulators require that systems meet performance goals. They don't care how the system is built. They just want it to function well. This is the preferred approach. It creates a favorable climate for innovation. Technical progress is not likely to quickly outdate the law.

The final idea I suggest you copy:

They have a short, simply worded law and a longer explanatory booklet. The booklet can be more easily updated than the law.

Both the full text of the Arizona greywater law and the full text of their greywater guidelines booklet are in your packets.

The Arizonans did excellent work, but they left some good opportunities for New Mexico to do better yet.

A New Mexico explanatory booklet should use updated drawings that show better designs and hardware choices.

Arizona allows lawns to be surface greywatered. I recommend against it. However, this is my most widely violated recommendation, and the violators are not getting sick. You should think about whether you want to allow lawn greywatering in New Mexico or not.

New Mexico should allow the reuse of kitchen sink water if the builder can demonstrate that their system can handle it. Arizona is planning to add this feature to their law.

I suggest New Mexico tighten restrictions on surface ponding of greywater.

A well-designed law in New Mexico would touch many of your constituents’ lives directly and immediately. Rather than label them as outlaws, it would recognize and support an activity that benefits society and the natural environment.

More info

Health Threat

Health risk is the only real objection raised to liberalization of greywater reuse.

While this is a theoretical possibility, the actual threat seems to be very small or nonexistent.

Greywater systems just aren’t that dangerous. Systems that process toilet water, which contains 99% of the pathogens, are critical. Systems that process greywater aren't.

As soon as people piped water indoors, they sent it back out in drain pipes that just dumped on the ground. Greywater use in systems no where near as well-designed as the systems you could legalize has been widespread and long term. Still, there has not been a single documented case of greywater-transmitted illnesses in the US.

How much water can we save?

For simple homeowner installed retrofit systems, 15% savings is realistic. Professionally installed systems in new construction can save 50%.

See also:

Greywater policy center