Perspective: Rainwater vs Greywater in San Diego

Prepare yourself for some wild numbers!

Check this out San Diego!  You want to see a crazy cost comparison?  Assume that you have a 2000 square foot house.   Not crazy big for SD.  At 600 gallons/1000 square foot/inch of rain, this looks like 12000 gallons of rainwater coming off your roof for the year.  Assume you wanted to store most of it, and you have room for 9000 gallons of storage on your property (above ground, round plastic tanks are cheapest).  You may want all the water to keep your 500 square foot lawn green (which wouldn't quite be enough anyway) or maybe you have a thriving food forest which is providing you with high quality organic food (that sounds delicious!)

If you add up all the $$ it's going to cost to install 9000 plus gallons of rainwater storage, it will be in excess of $10,000. If you want to tie it into a pump and feed it into the irrigation system that will add another $2000 or so.
That comes out to over $1/gallon.  

Now let's look at shower greywater for a four person household:

Mom showers 15 minutes a day (are they using low flow showerheads (2gallons/minute)?) = 30 gallons/day
Dad showers 5 minutes a day = 10 gallons/day
2 kids at 20 minutes a day  = 80 gallons/day
____________________
Total = 120 gallons/day x 365 gallons for the year = 44,000 gallons +/- for the year

If you are installing a permitted system for 2 showers to gravity flow into mulch basins on your property, this could add up to maybe $5K, on the high side.  Note, you don't want to use this on your lawn!

That comes out to $0.11/gallon

Now if you want to compare that with water coming out of your tap.  If you look at your water bill, you are charged per HCF (1 Hundred Cubic Feet = 748).  Depending on which tier you are in and what city you live in  this could be about $3-6/1HCF which adds up to about to between $0.0004 and $0.0008 per gallon.

Water is cheap San Diego.  But everything comes at a cost!  There's tons of literature about the cost of bringing water to San Diego from hundreds of miles away from the Colorado River and from the Delta up in Northern California.  Make an informed decision.

Greywater: A Simple and Effective Resource for Water Starved San Diego

Greywater is water that comes from showers, sinks, and laundry before it combines with toilet water.  Kitchen sink water is blackwater in California.  Many people are nervous about using greywater for fear of contamination and the ick-factor.  Greywater use is not only common but legal and encouraged by public utilities all over Arizona, New Mexico, Australia, and many other parts of the world.  There are over a million users in California alone, and no instance of anyone getting sick from greywater use.

A UCLA report, titled "Graywater: A Potential Source of Water," estimated that if 10% of Southern Californians implemented graywater systems for their laundry, showers, dishwashers and faucets, "the potable water savings would be equivalent to, or larger than, the capacity of a modern, large seawater desalination plant such as those proposed for California."  That’s exciting news for taxpayers!

Last year, San Diego experienced a massive power outage.  Millions of gallons of sewage spilled into the Los Penasquitos Lagoon and the Sweetwater River due to lack of backup power at the sewage treatment plant.  It is clearer than ever that homescale greywater use has its place in our communities.  If each residence around San Diego, and beyond, had laundry and shower greywater systems in place, we could reduced the amount of water being sent from each home to the sewage treatment plant by half. This is a small investment in infrastructure compared to the grand scale of municipal water treatment.

The landscape is designed to capture and treat this slightly used water in the soil, with mulch basins and plants providing high levels of microbial activity which bioremediate any solids or pathogens in the water. This compared to high volumes of water with added solids and pathogens from toilets spilling out directly into our waterways?

Greywater regulations changed in California in 2009 to allow simple Laundry-to-Landscape systems with no permit required, and simple shower systems with specific requirements and a permit.  A simple Laundry greywater system can cost as little as $150 in parts if you do it yourself or as little as $500 if you have a professional install it.  With the potential for producing a couple thousands of gallons of nutrient rich reused water, this is a great investment!  Shower systems can be more complex, especially if you are on a slab, or your bathroom is upstairs.  You may have to hire a plumber well versed in greywater to install your 3-way valve and a landscaper well versed in water conservation, or a water harvesting professional.  The simplest shower greywater systems may cost as little as $600-$800 depending on a multitude of factors including if you have a crawlspace, what kind of slope you have in your yard, how much water is being managed.

A basin designed to collect the water from the
Laundry Machine at the drip line of the tree.
This basin will be filled with mulch.

Many people think of storing greywater and using it in existing irrigation systems, but this is a far more expensive and complex setup than most people need, involving pumps and filters.  A gravity fed system is efficient and cost effective.

Most anyone can implement a Laundry greywater system if their laundry room is on an outside wall, or in an outside building.  By adding a three-way diverter valve to your washing machine hose, you can control whether to send your laundry water out to your yard or down to the sewer.  This is important for instances where you may use bleach or have some other toxic chemicals in your laundry or it has been raining substantially and your yard is saturated, for example.

By keeping the water in a 1” line, you keep pressure from your washing machine pump, allowing you to take the water slightly uphill or over longer sections of garden, and do not constrict the pump flow causing burn out.  From here, you can simply pop a hole in your outside wall and bury your line out to your trees or shrubs.  You can put in as many branches as you need, adding ball valves to control the flow to specific locations. 

It is important to calculate your water budget, which is affected by what kind of machine you have (10-50 gallons) and how many loads a week you do.  Then you can take into account what landscaping you are watering and how much water it will need in an average week.  This way you do not spread the water too thin, or overwater your plants. 

It is also important to use your water on plants that will respond favorably to this slightly more alkaline and saline water supply.  Typically lawn is not ideal since there are potential pathogens in this water and, when a lawn is used for recreation for pets or people, they may come into contact with these pathogens.  You should not water root or leafy green vegetables with this water for the same reason.  Fruit or other trees as well as shrubs are ideal.  Some natives are sensitive to salty soils and may not appreciate this water.  If you are not sure, ask at your local nursery, or contact a water harvesting professional.

Which soap you use matters.  Check out the ingredients and avoid anything with sodium in any form.  Usually powders have a sodium base.  Avoid borax as well.  Two sure bets are ECOS, available at Sprouts and Costco and Oasis, available at Peoples Co-op or online.

There are now more resources in San Diego than ever to create efficient and effective greywater systems.  Look for water harvesting workshops and tours especially with the San Diego Sustainable Living Institute, water harvesting professionals, articles and blogs.  The Olive Branch Green Building Supply has started stocking greywater materials and offering educational resources for greywater. 

Justifying Rainwater Collection: Calculating the True Cost of Cheap Water

The other day I got a question that I get all the time.  It is a good time to answer this question in a public forum, especially considering the rainy season is almost upon us.  We can all benefit from changing the way we think about our water resources.

Q:  In running the numbers for rain barrels, filling a 1500 gal barrel twice equals 3000 gal or 4 HCF. That's just under $15 (this is at tier 1 costs). which makes the payback for a $1500. system equal to 100 years. 

These numbers are hiding a lot of costs that we are not thinking of as we turn on our tap and let the water flow out at pennies per gallon.  What if we start to factor in some of these hidden costs?  What would our cost/benefit analysis look like?

First of all let's readjust our expectations of the costs involved in setting up a 1500 gallon tank.  You can get a 1500 gallon rainwater tank from The Tank Source, located in Alpine for about $600, plus about $100 for shipping.  This tank has about an 8' diameter, which is certainly doable for some but not all residents.  I think a 1000 gallon tank with a 6' diameter is a little more realistic for most urban homes here in SD, at a cost of about $600 plus $100 for shipping.  You can see that it is more cost effective to get the largest tank you can.  If you want to set this tank up yourself, you would need a couple filters at a cost of about $80.  You will need some pipes and parts, totaling between $100-250 depending on the distance you are taking the water from your house and a few other nuts and bolts.  This can look like as little as $800!  Or if you have a professional install this tank, you may expect to pay about $400-$500 in labor costs.  Now we are getting up to $1200-$1300.  But did you know that the City of San Diego is offering up to $200 in rebates for rainwater tanks?

Some of you may be wondering if it is even possible to get 1500 gallons of water off your roof in our arid climate.  The answer is ABSOLUTELY!  Check out this amazing rule of thumb and compare it to your situation:  A 1000 square foot roof will yield 600 gallons of water in only 1" of rain.  It rains about 10" here in San Diego.  So you can fill this tank up in less than a third of our rainy season, which means you may be able to fill it up THREE times even, if you can find something to use the water on in between rains.

Those are the basic nuts and bolts of this example system, but let's delve further into the cost of water. Consider that water in Southern California is excessively underpriced for its actual cost with regards to energy, environmental, and legal impact.  You can decide for yourself whether or not you think this is a true statement after we consider some additional information.  You could start by reading Cadillac Desert, by Marc Reisner to help you understand the intricacies of how and why our water infrastructure was built.  As we become confronted with the reality of the related costs associated with cheap water, prices will raise significantly, and any conservation tactics we have put in place before that time will greatly reduce our dollar cost in the future.

Did you know only 20% of our water comes from local sources?  The remaining 80% comes from both the Delta region up in the Bay Area and the Colorado River.  This means a few things.  First of all a drought that may be affecting other regions, and not us directly will certainly impact our water supply.  Also, there are legal battles ensuing over Colorado River water and Delta region water than may reduce the amount of water coming to Southern California.  Let's imagine you have a valuable investment like an established fruit tree, or many.  If there are drought restrictions in place that limit how much you can water your garden (kind of like last summer), wouldn't that water in your 1500 gallon tank become more valuable to you as asset protection?

Did you know that 20% of California's energy costs are associated with moving water around the state, including the incredible feat of pumping our water supply from the State Water Project 1,926 ft over the Tehachapi Pass north of LA.  So let's add some energy costs into the cost of getting our water out of the tap.  Let's also factor in the benefit of having an emergency water supply on hand if power is disrupted for any reason for any length of time.  Maybe that water supply is for protecting your established food production, or maybe it is even more valuable as a drinking supply.  Can you calculate what bottled water will cost per gallon in an emergency and compare that to the cost per gallon of the water you have stored in your tank?

We have only been addressing water supply issues, but what about the value of mitigating storm drain runoff?  How many of your tax dollars are allocated toward dealing with storm drain pollution, or even urban flooding associated with the massive volume of runoff created by paving over as much as 80% of our permeable surfaces in urban areas?  If all of us put at least some of our rainwater from our roof into rainwater tanks, and then redirected the remainder of our runoff into our gardens, which were landscaped to hold water using basins, mulch, and appropriate plantings imagine how much money could be saved at many levels.  Think of tax dollars and grant funding being used to clean up waterways that get inundated with polluted storm water.  Think of tax dollars being used to repair and clean storm drains every season!  Think of redirecting this money to funding education in schools and communities and rebates for systems that serve the double purpose of augmenting a limited local water supply!

Now if you are going to use this very expensive water source to keep your lawn green, you might not consider a rainwater tank cost effective, especially if we look at some very simple figures.  Lawns typically require about 50" of water to stay green throughout the year.  It rains about 10" here in SD.  If you run the calculations of applying 40" of water to 500 square feet of lawn, you realize 13,000 gallons of precious water are required to keep that lawn green.  It is hardly worth storing 1500 gallons, or even 3000 gallons to maintain this aesthetic.  Why not get rid of the lawn and plant something that can be maintained with that 3000 gallons, like natives, or Mediterranean plants such as the Nifty 50.  Native plants maintain a diminishing local ecology which is being threatened by paving and invasive plants.

There is great value to using our precious water resources to grow food locally.  There is an even greater water footprint than what we see on our water bill every month, associated with goods and services we buy and support.  Be on the lookout in the Union Tribune for an article about this in a couple of weeks.  Try to imagine that an orange brought in from Florida has a higher fossil fuel cost, which has an associated water cost, than something grown here in California.  Furthermore, an orange grown in an industrial agriculture setting will have a higher associated water cost than one grown in your backyard.  Furthermore an orange grown on rainwater in your backyard will have the lowest water footprint of all!

This is a lot to take in when you are justifying the purchase of a rainwater tank.  Food for thought: why not consider using greywater!  A simple Laundry-to-Landscape system which sends your laundry water (non-toxic, organic, sodium-free soap included) to your trees and shrubs can cost as little as $150 in parts, or $500 installed by a professional.  If you run 4 loads a week on an older front load washer at a rate of 35 gallons per load, you'll be making over 7000 gallons of water available to your landscape over the course of a year.  If you combine this with trees and shrubs that are actually producing food for you that you don't have to buy from the store, and you take into account the additional nutrient content of this water as a fertilizer that you don't have to purchase and will increase production of your plants, you can see some pretty astounding justification for this water conservation strategy!

For more information about these simple strategies and specifically what is possible in your own space, check out the upcoming Water Harvesting Tour this Saturday (http://www.facebook.com/events/408710185858142/)


or contact Brook Sarson with H2OME at brook@h2o-me.com to schedule a consultation!

Upcoming Events

Make Your Own Rain Barrel Workshop

Saturday, February 18, 2012. 10:00am-12:30pm

Location: City College

Are you ready for the rain? If you’ve been looking for a cost effective way of saving rainwater, we are offering a solution. Come and make your own rain barrel to take home!

We will provide clean, recycled, food grade 55 gallon plastic drums along with a kit of parts to tap it for a hose fitting on the bottom and an overflow on the top, as well as mosquito-proofing options. You will be able to drill your holes and assemble your barrel onsite.

The class will begin with an educational seminar covering various facets of water harvesting from understanding what your rainwater potential is, how to use your rainwater, how to accommodate runoff in your landscape, as well as greywater use and regulations.

The cost of the class is $75, If you would like to participate in the workshop but do not want to take home your own barrel, the cost is $25, sliding scale. If you would like to purchase an extra barrel and parts, the cost will be $50. Cash or check will be accepted. Don't forget that you can apply for you barrel rebate of $27! $5 of your fee will go to Seeds, the Urban Farm at City College to further the programs they offer.

This will be a great opportunity to connect with community members and learn more about using our water resources.

Please RSVP by Monday, February 11 to ensure your spot. Spaces are limited to the first 15 people to sign up. You can RSVP to brook@h2o-me.com or call 619.964.4838