No math involved

In the current state, stage 2, all households are allocated 45 gallons per person per day for indoor use. Outdoors, we’re to reduce our water consumption (for landscaping, swimming pools and the like) by 35% when compared with the equivalent period in fiscal year 2019-20 (July 1, 2019, through June 30, 2020), and are to only run our irrigation systems on two specified weekdays, depending upon our home address: Mondays and Thursdays for odd numbers (or no address), Tuesdays and Fridays for even numbers. As for commercial enterprises, they have separate limits of their own.

Forty-five gallons of water per person per day may not seem like a lot, but it’s actually quite reasonable. Given my own water bills, after subtracting out the water my household uses for irrigation it’s clear that for some time my wife and I have been using substantially less than 90 gallons per day (45 gallons multiplied by two people). Even with our outdoor usage, in fact, our average daily usage is only a little over 90 gallons.

How? Years ago, we swapped out our shower heads, installed low-flow toilets, switched to water-saving appliances (particularly, the washing machine) and developed good habits such as taking short showers, using buckets to capture water while the shower is getting warm, and only flushing toilets when truly necessary.

As for our outdoor use, we once had an in-ground swimming pool, but got rid of that several years ago. We no longer wash our cars on the driveway, and instead take them to a commercial car wash that reuses its water. We haven’t had a lawn for many, many years. And what landscaping we do have consists in large part of California native and other drought-tolerant plants (we do have a pair of small fruit trees, and a number of fruit and vegetable plants that require more watering).

Some years ago, we swapped our sprinkler system for drip irrigation.

And we have rain barrels, which although they aren’t capturing any real rain right now, serve as short-term storage for “warm up” shower water until it is needed in the garden. Finally, our sprinkler controller automatically adjusts itself depending upon the weather and only runs twice a week, in the early morning hours.

Our yard may be fairly water-wise, but are we saving 35% as compared with the same period three years ago? Who knows? Even though our water bills (which I have from 2015 on) show us saving are some total amount compared with back then, what I cannot do is determine just how much of the water we used in 2019 was for internal use, and how much of it went to the yard.

What I can figure out, at least roughly, is how our usage is split between indoor and outdoor use for the current billing period. Thanks to Redwood City’s My Water website (https://mywater.redwoodcity.org), I’m able to export our daily usage numbers for the current billing period (and only that period, it seems; in particular, I cannot seem to get My Water to give me similarly detailed data for the 2019-20 time frame) and put those numbers into a spreadsheet. Then, for the days when our irrigation system ran, I estimate our indoor usage by taking an average of the surrounding days, days when the system didn’t run. By subtracting the indoor usage estimate from day’s total, I’m left with the amount, roughly, that we used outdoors.

Fortunately, for those not into crunching numbers, you needn’t do any real math. For one thing, Redwood City residents living in apartments, condominiums and townhouses with little to no outdoor planting space can largely forget about outdoor usage, and instead focus on using no more than 45 gallons of water per person per day.

As for those of us with yards, since we have no way to realistically determine whether our yards are consuming 35% less than they did back in 2019-20, we, too, can skip the math. According to the city, as long as we use outdoor water as efficiently as possible, and as long as we follow the requirement to only irrigate on the designated two days per week, we should squeak through. Hopefully they’re right, and we can avoid higher (and far more restrictive) stages — along with any more math!

Greg Wilson is the creator of Walking Redwood City, a blog inspired by his walks throughout Redwood City and adjacent communities. He can be reached at greg@walkingRedwoodCity.com. Follow Greg on Twitter @walkingRWC.