Rainwater Harvesting &
How it fits into Green & Sustainable Methods
We have visited this subject at various times over our years in Costa Rica. It recently resurfaced again this past week due to questions directed from one of our readers and a prospective home builder. It is far from uncommon for a client to spur on an investigation into a product, method or concept or in essence to bring such to the forefront of thought. Hence once again I thought this subject more than warranted a post/article for others to, pardon the pun, harvest some knowledge from. Thanks Tim for spurring me into action to answer questions and concerns of many other followers here on this blog. Before we get started let’s get it straight as to what is priority one regarding any discussion or decisions being made with regards to sustainability. Consumption rules the game whether we are talking water or electricity. First control your use then deal with where your supply is coming from. So for this discussion about water it goes without saying that one MUST USE low volume flush toilets that have come a long way in the last 15 years, as well as shower heads and sink taps with aerators and flow controls and never aerial spray your garden so as avoid throwing your precious resources down the drain or evaporating.
A Dose of Reality:
The data, according to The Washington Post, provide the most compelling and detailed picture yet of the status of vital water reserves hidden underneath the earth’s surface.
The paper further reported:
Twenty-one of the world’s 37 largest aquifers — in locations from India and China to the United States and France — have passed their sustainability tipping points, meaning more water was removed than replaced during the decade-long study period, researchers announced…. Thirteen aquifers declined at rates that put them into the most troubled category. The researchers said this indicated a long-term problem that’s likely to worsen as reliance on aquifers grows.
For some time, scientists suspected that humans were exacting a toll on the globe’s underground water supply. However, the NASA data and study were the first to actually detail major aquifer draw-downs as they struggled to keep pace with agricultural, human need and industrial demands.
“The situation is quite critical,” Jay Famiglietti, senior water scientist at NASA’s Jet Propulsion Laboratory in California and principal investigator of the University of California Irvine-led studies, told the Post.
What happens when your water just disappears?
The Costa Rica feast or famine climate does indeed lend itself or demand one pays attention to water resources when we go from bone dry for a good part of the year to swimming up to your neck in water. The following is a perfect example of how critical this issue can be in the enjoyment of your home and of course security of your investment in such. The Guanacaste is the worst/best situation to employ rainwater harvesting. A perfect example is the house we live in at Playa Conchal while doing our build at Playa Grande. I have had to haul water 8 kms from our build site to our home as there is next to zero water in the two wells of this project. One well goes dry by January and the other only produces maybe 10 – 20% of the needs of the project from January until the rains start again. This is a very dry part of the north Guanacaste in the first place at about 48″ or 1.2 m of annual rainfall but this tough environment has been considerably aggravated by the sheer stupidity of MINAE (environment ministry in charge of water wells). Less than 2 kms from this home is the Reserva Conchal Resort which has a few hundred condos plus employee housing along with an 18 hole golf course. As many will know a golf course in this kind of hot and dry climate consumes a massive amount of water and in this case all of it comes from the aquifer since their is exactly zero rivers or lakes in this area. To appreciate how insane of a move this was lets look at a typical California golf course of 110 acres normally consumes about 90,000,000 gals of water a year. So that would equate to enough water to feed 4,500 homes for 5 months of the year at 265 gals per day per home. Most assuredly there is not that many homes within the reservoir of Reserva Conchal’s wells, so lets just suffice to say a perfect example of, “TOTAL INSANITY!”
So MINAE issued licenses for the project to drill how many deep wells to provide the water to this one project while starving all the neighboring homes with shallow wells from getting water during dry season. Surprisingly anyone I have talked to does not quite draw the connection between the cause and effect of what Reserva Conchal did. If your neighbor, who could be 5 to 10 kms from you, bores down into the aquifer below your wells they get the water prior to it reaching up into the pump zone of your well. In essence you are left with the hind tit, as it were, with zero or next to zero water available for 70% to 90% of the dry season.
The aquifer is typically just like one huge sponge so the water will move around in it would through the easiest path horizontally thanks to good old gravity. Hence why the offending water pig could be a long ways away from you and your dry well. Also way out of sight and mind but just the same when those with deep enough pockets drill down further, than those with less money and resources, will get first dibbs on what water is available. Yes an incredibly stupid and short sighted use of scarce water resources. This is even more offensive when one considers that the state owns all water resources in Costa Rica regardless to who owns the land above it hence why you need a concession (license) prior to putting a well into service for any use. In many circumstances you will never ever get such a license if you are too close to another well or have an alternative water supply like A y A or an ASADA. (water cooperative) Somehow Reserva ducked this or MINAE was grossly incompetent or paid off or more likely politically influenced to make bad decisions by the original developers where water rights were forgone by the fact that MONEY TALKS!
This is a perfect example of how water can so drastically affect your investment. When this reality hit us hard in April I saw the situation and advised our client that his home in this waterless project is of seriously diminished value. No one will buy in this project at replacement value once anyone tells them about the water situation. No one in the project can use or fill their swimming pools during the summer which happens of course to be the rental season hence many prospective vacation rental clients will just not rent if they can’t use the pool. Worse yet any of the empty lots in this project cannot ever build because the administrator CANNOT very well issue a water letter that is required in order to get a building permit from the municipality. Hence those lots are basically worthless or worse a liability with ongoing HOA fees assuming the owner is stupid enough to pay expenses on what is in now in essence nothing more than pasture.
This leaves the affected neighborhood in this pickle with but five choices:
- 1. Sue Reserva and the government for blatant stupidity or breach of state law = waiting 10 years for a process to unfold
- 2. Haul water at $452 a load for 12,000 ltrs / 3,174 gallons (24 days of use) = $2,825 yr -Take note the cost of trucking versus water from AyA would carry a bill of $20.40
- 3. Harvest 20,000 gal of rain water and store it in an $8,000 tank = payback 2.8 yrs
- 4. Build a desalination plant for a few million
- 5. Learn how to do a really good rain dance
Now let’s move onwards with getting more into the green concept and more details on rainwater harvesting as that is really the only economically viable solution to this kind of situation. This is hardly a new concept for me from having grown up on the prairies where water is a rather scare commodity with an annual rain fall of a mere 14 inches (35 cms). Almost everyone out on the farm had cisterns to hold rainwater as well as many of the older homes in town did as well. This feature did wain out over the years as far as new homes were concerned but let’s not assume the more modern methods are better or more sensible and often a complete opposite of sustainable.
While on this subject aside from the universal availability I also suspect many readers have no idea what soft rainwater is actually like to use in your home. Softwater is far better to wash with for both bathing and laundry and actually requires substantially less soap to be used to get the same cleaning effect. However it is not something one wants to drink due to the lack of minerals which makes it far less than tasty. Although minerals is what makes spring water taste so good but the lack there of in rain makes it not suitable for drinking nor healthy when we aren’t getting those minerals in our daily dosage. A further benefit to that lack of minerals means the whole water system including showers and toilets which all require way less maintenance over the years as there will be no buildups of mineral deposits anywhere. Very hard well water always causes drastically more maintenance by shortening the life cycle of all components to the water system.
Also the reality is that the actual potable water use in a home is a minute part of the total water consumption (-5%) hence it is not actually expensive to acquire your favorite drinking water from a spring or even using horrifically expensive bottled water. Another health benefit to having your own drinking water supply is that it would never have chlorine in it which of course no one should be consuming in any way shape or form. Those using such a system like this will actually have parallel systems where a mini system feeds the cold water of the kitchen, ice maker and possibly vanity sinks whereas the major system will feed the toilets and showers and gardens. With our PEX networks this is no more expensive since we already have individual lines to each service. It will require more manifolds but each being smaller and a second pump for the potable water however these are cheap pumps due to the low demand hence a maximum of 1/2 hp which would run for typically 10 to 20 years. It would require a second pressure tank but again a small one is all that is required once again due to the low demand. The big issue however is that this type of dual system is something that in all practicality HAS TO BE DONE during construction. Modifying an old system not configured in this way is what is expensive as well as being a royal pain in the ass to actually accomplish.
This type of water system also allows you to keep your personal vegetable garden growing during summer if your home does not happen to be parked by a full season river or creak. The one caveat to that is that you have to use an underground weeping water system as above ground watering has an 80% loss factor from evaporation. It would be nonsense to oversize cisterns to catch extra water that you only end up throwing away via evaporation. Its not like Costa Rica needs to raise the humidity level any more. Also on the typical larger sized lots our clients have we always position the septic leach field so that it provides the underground water system to feed the garden whether that be just to keep a year round green area and/or to feed veggies. Also the extra nutrients that are carried along with septic run off in the field means anything growing above that field will grow like crazy, way beyond the norm. In essence the fertilizer is carried with the water into the leach field. Basically killing two birds with one stone naturally. Yes there is those who push for recycling wash waters however along with such comes a drastically more complicated system both for installing as well as for maintaining. Just using the wash waters to keep a perpetually green area and garden space does indeed provide a simple to install and maintain system not to mention a very pleasant environment. After all one of our greatest benefits to living in Costa Rica is this green garden ambient!
In any zone where there is scarce water resources this is an absolute no brainer by simply using long term planning in your home and yard’s infrastructure. Few people realize the incredible amount of water that actually can been caught off of a roof in Costa Rica. Oh and NO we do not need a license or are we in any way restricted from collecting water as has become a bizarre but common fact in the USA.
One of our typical roofs running around 2,152 sq. feet or 200 m2 will catch the following amount of water. Take note that this is total roof area included the eaves, carports and terraces so this does not mean these stats are from a big home on North American Standards as far as in wall standards are concerned.
- North Guanacaste = 240,000 ltrs or 63,492 gal
- Central Valley = 440,000 ltrs or 116,402 gal
- Jaco = 600,000 ltrs or 158,730 gal
- Manual Antonio = 700,000 ltrs or 185,185 gal
- Dominical = 900,000 ltrs or 238,095 gal
Most homes would consume 180,000 to a max of 360,000 ltrs per year depending on the person load as well as your habits good or bad.
Your location in the country will affect how long your dry season is as well hence most certainly will affect the size of storage cistern one would require. In general for sizes of any significance forget plastic tanks on the basis of cost as well as cosmetic factors. Plastic works for small tanks 10,000 ltrs or less is their viable range. Plastic cannot go in the ground either as they will easily collapse when empty plus you most likely do not want to look at these in your yard hence you are going to have to hide them away somewhere which will mean more piping costs. Another big problem on most sloped lots is to actually find any space for them especially if you need 5 to 10 of these. Then the simple fact is that they cost about $.60 per gal to purchase which is 50% more than concrete.
Contrary to this I only use monolithic concrete tanks for their strength and much higher resistance to seismic activity, NEVER BLOCK. These can be buried underground and hidden from eyesight yet close to the house in the garage or driveway where the top can double as parking space as well as the top of the tank. Also makes it easy to send the water into them and to retrieve it as well by your water system. These tanks run around $.40 per gal depending on the configuration as the larger the tank the more economical it becomes simply via scales of economy. To be able to survive for a 5 month dry season with a 132 gal or 500 ltr per day water habit will require a 75,000 ltr or 19,841 gal tank which will run you right around an $8,000 budget. Take note though, if you have A y A water available at current rates it would take 25 – 35 years to pay off this tank from regular water bills and that is with building in a cost of living factor as their bills will indeed go up however I doubt the bill from the sky will do so. So this option is for where there is a water shortage during dry season or simply for those who want to be self-sufficient. Again all of this is only even remotely practical if done as part of a new home building process as a retrofit is going to double to triple your costs. Reality is though that anyone with tanks of this size will most likely never ever have a use for any public water system and most people once on soft water have no desire what so ever to go back to mineralized and chlorinated water. Plus wise people know that whenever it is possible to avoid chlorine will do so for long term health concerns by avoiding this known free radical.
In essence rainwater harvesting proves to be sustainable in all aspects of environmental concern, independence, better quality of life as well as personal health improvement. Instead of saving for a rainy day you are saving for all those dry summer days of enjoyment.
As always feel free to post questions, clarifications or comments below or via email.
Great article once again Trevor! Speaks directly to the problems we deal with in Avellanas – the Avellanas water woo’s – is what they call it, yes there is a name for the water shortage in Avellanas, lucky us!We will plan on the 20K tank, as the neighbors have all suggested as big of a holding tank as possible. According to them, if everybody had large tanks and ran from those, then the water shortage during dry season would not be an issue. So we were already planning on it.