From public service announcements on the radio to flashy ads in your inbox, we are inundated with ways to conserve water. We are encouraged to use faucet flow-restrictors, energy star appliances, rain barrels, irrigation controls, laundry-to-landscape and much more – but how do you know which will give you the best bang for your water-buck? Messaging often presses for ‘low-hanging fruit’, which is great but might miss the mark when thinking about scale of impacts. Here are a few tools to help you evaluate what’s best for your project.
Your approach will vary whether your project is residential, commercial, or hospitality. One of our first LEED certified buildings, back in 2009, was Niner Wine Estates. I remember calculating that low-flow plumbing fixtures would provide 30% savings, or 50,000 gallons per year. That seemed impressive until we looked at options for outdoor savings through irrigation efficiency and recycled water, and saved over 3 million gallons per year!
Project Types will vary!
So, the lesson was to focus on water savings for the highest water uses, rather than what seems easiest. Here are three sample project types to illustrate indoor vs. outdoor water use:
A multi-family project on a tight site should focus almost entirely on indoor plumbing fixtures, where going from a 2.0 gpm shower to a 1.8 gpm could make a huge impact. Conversely, offices use very little indoor water but can be big water consumers for ornamental landscaping, so native landscape and drip irrigation would be a smart investment. A boutique hotel might be a balance of both, with the added consideration for lots of laundry, triggering selection of high-efficiency equipment and maybe a laundry-to-landscape system.
Calculating water use – rough numbers
To dig into the numbers, first create a sort of balance sheet, knowing what your demands are and what your opportunities are. For indoor water, there is a standard table of uses available through Cal Green – how often a person, on average, uses a sink, toilet or shower. You can add for laundry, dishwashing etc. Usually, we plug in the California maximum then see if we can specify low-flow, but for a renovation you can start with your existing fixtures and see what you can save with replacement.
Here’s an example:
Once you know your indoor use, you want to figure out your outdoor use. Your landscape architect or designer will provide that, but to get a working number, it helps to use the EPA WaterSense Water Budget Tool.
Understanding your intial water demands, you can evaluate potential savings. Finally, you can then consider water sources, other than the potable water. Laundry and showers generate ‘graywater’ which can be used for irrigation, if applied without storage and under a layer of mulch. Rainwater can be collected and stored for irrigation. Depending on water volumes, systems can be engineered for filtration and storage, flushing toilets, etc.
In the table to the right, showers and laundry would cover all of the irrigation demand. Installing a rain barrel would be another option to supplement irrigation.
Don’t waste water, or your money
In summary, sure, every drop counts and why not add that aerator on your sink. On the other hand, once you understand the opportunities to save water for your entire project, you may find better strategies that make a significant impact – good for business, and the planet.
Drought-tolerant plantings can save thousands, even millions of gallons of water Credit: Niner Wine Estates
