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Greywater system at NRDC's Santa Monica Office

Anthony Guerrero

Posted May 22, 2014

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As most of the country delights in the rising temperature, the Western United States, including California, wonders what lies ahead for them this summer as they continue to face water scarcity issues. This has serious consequences for local communities resulting in water shortages and decreased access to quality drinking water. As California knows well, droughts seem to be occurring with increased frequency these days. Now, more than ever it is important to think of what we, as individuals and companies, can do to help the situation.

So what can we do?

One of the best ways to protect this precious resource is to conserve the water we do have and use it in the most sustainable way possible. Installation of a greywater system, such as the ReWater System we recently put in at our Santa Monica office, allows you to capture greywater and reuse it for landscaping. Since 80% of municipally supplied water is used in buildings it is important to tap into this resource. We are able to monitor all of the water consumed within our building using the Noveda system, a sustainability reporting tool providing us with up to date information, so we are able to make adjustments if needed. Our building may be on the smaller side, but we are taking steps to ensure that we reduce our water use overall and use what we have in the most efficient way possible. “It is a great way for NRDC to showcase one of its priority initiatives (ensuring safe and sufficient water) and help out our own community,” said Rene Leni, Office Administrator of the Santa Monica office and also the person who led the installation of the system in the office.




Wait, what exactly is greywater?

Grey water is the water discharged from your bathroom sinks, showers, bath tubs, and washing machines, don’t worry not the toilet. It is water that can be safely filtered and reused for non-potable purposes.

Is that safe, how does it work?

The ReWater System allows for water filtration as it is produced from showers, sinks, etc. The greywater is pumped to the surge tank where it will wait until signaled that there is a need for irrigation. At this time the greywater is sent through a sand filter to remove any harmful mater. After filtration the water travels to an irrigation controller, which determines the need of the surrounding landscape and uses an underground drip-irrigation network to supply water to the area. At the end of the cycle the system automatically backwashes itself, cleaning the sand filter so it is ready for use again. The system also stores rainwater collected during rain showers. This provides an additional resource to supplement any excess needs. Because of these measures domestic water use for irrigation is a last resort.  




How does this help the surrounding community?

This allows us to conserve water in two ways, first through collection of rainwater and greywater and second through efficient landscaping techniques. If we are able to capture water in this way we can reduce the need for municipal water supply to our building. While this creates a savings for us, it also allows more efficient allocation of resources around the city.

The efficient landscaping techniques allow for the water collected to keep the landscape irrigated without drawing on the municipal water supply. We can keep ecosystems thriving without any additional water use from what we are already consuming within the building. Planting native species is also helpful in that these local species are used to the Southern California climate and can withstand the drier conditions. Drip irrigation is significantly more efficient than the use of sprinklers, especially in climates resembling Santa Monica, where more than half of the water sprayed evaporates before it can be used by the plants. Soil acts as a filter, removing surface acting agents found in laundry detergent that would normally not be filtered out at a treatment plant and concurrently allows the soils to become more nutrient rich as it absorbs some of the remnants of ingredients in the water. This method also protects the surrounding area from runoff and stormwater pollution. Ideally all this water is being retained onsite and so it does not reach the sewer system. However, as an overall benefit it will lessen the load on the municipal sewer system, preventing overflows into the local waterways. Otherwise the water would add to the problem of combined sewer overflows resulting in polluted runoff going into the surrounding bay (this water does come from the toilet); not something you want to be swimming in.

How does this create savings?

Savings are achieved directly through the conservation of water from the source and also the efficiency with which the system irrigates. The Santa Monica office has seen savings on their water bill because of the effectiveness of the grey water system. Additional savings can be result from reductions in stormwater through control of run-off pollution.

We have also seen savings through energy reductions as we do not have to pump in additional water and the irrigation occurs through a drip system which requires no energy. This is another step forward on our journey to becoming net-zero.

Sounds great, can I get one?

These systems can be applied to your home as well. A typical single-family home will reduce its water by 20-30%. Using a drip irrigation system this also means less time spent watering (something I think we can all get on board with) and more efficient use of the water you already use.


Written in collaboration with Marisa Kaminski

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