Let it rain. Let it rain. Let it rain.

Very rapid housing development and 
dwindling water resources may 
soon become San Miguel’s next challenge 

Conscious that water is a scarce commodity in this semi-arid part of the world, when we built our house we included three cisterns to collect rainwater from our roofs. The side-by-side cisterns are located in the back of the house, in the space created by a pretty steep slope, tucked under a large terrace.

Total capacity is approximately 325,000 liters or almost 86,000 gallons. Were we to remove the concrete cover (the terrace floor), and the two dividing walls, the combined system of cisterns would resemble a quite large swimming pool, approximately 14.3 meters long, 6.5 meters wide and 3.5 meters deep.

Annual rainfall in San Miguel is not insignificant, about 24 inches, though almost all of it comes between June and September. The rest of the year is dry as dust, which we get quite a bit of.

The two dividing walls between the three cisterns each have one large pass-through valve at the bottom that allows us to isolate the compartments for cleaning or repairs, such as we’ve been doing now—and which has turned out to be quite a chore.

After all that work, the cisterns were quite clean except for a sediment of very fine mud. There were no cracks on the walls or any other repairs. No mold or creepy-crawlies.

Now what we need is rain!

Félix emerging from one of the cisterns, during
long-postponed scrubing. 

Up to this year, the rainwater reserve plus a once-weekly injection of water from a community well nearby, had kept us supplied. That, plus some conservation measures, such as low-flow faucets and toilets, and a drip irrigation system in some parts of the yard.

For the past eighteen months, though, the community well system—if one could call it a “system”—has been sputtering for reasons yet unknown. We haven’t received our normal share of water for at least two months, and have had to summon 10,000-liter water trucks, known here as “pipas,” to make up the shortfall. Each pipa costs about fifty dollars.

The rapidly rising price of pipas, from seven hundred to a thousand pesos per trip during the past few months, suggests that scarce water is becoming a problem. Indeed, we’ve also noticed a growing number of pipas, usually painted blue, making deliveries around town—another bad omen.

Large as they are, the cisterns fill quite quickly when we have a heavy and consistent rain for three or four consecutive days. Except that the rainy season is not expected to start until June.

We sized the cisterns based on the square meters of roof surface of the house. Stew and I are often amazed, and pleased with ourselves, by how much planning and calculation we made during the design and construction of the house, a process that was greatly helped by one Werner Stubbs, an excellent architect and contractor well versed in “green construction,” who seemed to anticipate all our preoccupations and had answers to them.

The roof over central part of the house is sloped and covered with traditional Mexican clay tiles. The water from there is captured by long gutters and directed to the two wings at at each end of the house which are flat-roofed.

At each end of the terrace are two rainwater filters  
that double as cactus planters.

From there, two four-inch downspouts, hidden in the exterior walls, direct the water to two coffin-like filtering chambers. These chambers each have fine-mesh screens and gravel through which the rainwater passes before flowing into the cisterns.

The water collects in the cisterns and is pumped by an electric pump powered by solar panels, to a pressure tank in our small basement. There, the pipes split the water supply in two—water for domestic use which is filtered, and the rest for outside faucets used for watering plants, washing cars, etc. that can be used as is.

Contrary to some people’s fears, rainwater—unless you live in New Delhi or upwind from an oil refinery—is quite clean and soft. Our drinking water goes through a three-step process of filtration, including an ultraviolet light, plus a softener. The filter cartridges are changed quarterly by a local plumber.

Still, at this time of the year we’re running out of water. In San Miguel, where there is rampant construction of dense housing subdivisions, some with golf courses, the municipal water supply might be strained soon if it isn’t already.

Welcome to our laboratory: (l. to r.) the pressurization tank, an electric water
softener, the ultraviolet light (the long horizontal tube), and below that, a filter
to catch solids and a charcoal filter to get rid of odors. 

Visionary planning is not a strong suit of the city fathers and mothers, particularly vis-à-vis the lure of more tourists, residents and money. One does not ask too many questions during a downpour of cash.

Someone tried to sink an unlicensed well about a kilometer from us, but after a month of much banging and belching by an ancient drilling rig, the project seems abandoned. No one knows if the water authorities shut it down, the owner ran out of money or they just didn’t find any water.

Apart from the malfunctioning of the community well, the problem for us might be a growing forest of trees we planted, about one hundred, that have to be watered every one or two weeks.

Solutions are not clear, apart from calling a pipa every three weeks or so. The cost is not exorbitant given that our off-the-grid house has virtually no other utility costs. Another is to explore, i.e. Google, just how much water grown evergreens need. Felix is applying about ten gallons a week each, which seems too much.

Apart from that, I can only think of prayers. Or maybe singing a few bars of Eric Clapton’s catchy 1970 tune, “Let it rain.” Go ahead and play it.

As I was finishing this post late yesterday, Stew came in to the office and announced it might, in fact, be starting to rain. Out the window the clouds seemed auspiciously gray and gravid with rain.

But after a few timid droplets, nothing came out of it.

19 thoughts on “Let it rain. Let it rain. Let it rain.

  1. Yes, here in Mexiquito yesterday early evening I smelled rain, and then there came fat drops, splatting one by one on the patios. I shut doors and windows but for naught. It never spit enough to totally wet the stones. Though while I could smell it I though how delicious.


  2. I worked as hydrolological engineer, and also worked for a UV filtration manufacturer. The system you have is impressive, the only stage above it (and unnecessary) is reverse osmosis.Relating to transcontinental water pipelines, if the USA wants to start a war with Canada, it will be over water. Behind the scenes, there have been a number of skirmishes.


  3. I just arrived in Mexico City yesterday, and last night there was a thunderstorm. There have been quite a few good rains here in the last week or so… it's as if the rainy season is not waiting until June.


  4. This comment came to me via email from Jeannie Schnackenberg, who used to be an engineer at the Chicago Metropolitan Water Reclamation District:”Re: your blog post – I'm curious to know why you have a water softener for the rainwater? And you said it is “electric” – not ion-exchange? Have you ever tested the hardness of the water pre and post “softener”.


  5. We got this water softener because we anticipated that rainwater would only get us so far and then we'd have to rely on well water, which around here is pretty hard. We were concerned about getting those hard-water rings in the toilets and elsewhere., like we used to get when we lived in San Miguel proper. We don't have them which to me suggests the softener is working. We bought the electric softener, photo included, from Don Pedro hardware store, for $145 US. It's about the size of a cigar box, with a wire, and a small transformer, that you plug in at the beginning of the filtration chain. Then there are two wires, about two feet long at each end of the softener that you wind around the water pipe, before and after the softener. I looked up the instructions, but unfortunately it doesn't explain how it works, just how to hook it up. Thanks for your question.This is the website: http://www.aconsacr.com/wp-content/uploads/2016/06/Acondicionador-de-Aguas-Duras-SS-1-Helvex.pdf


  6. The only possible clink in our filtration system is that I've heard that as the water levels in the local aquifers drop the concentration of heavy metals such as lead, arsenic, or whatever, increases. I don't know if osmosis filters solve that problem. Never mind a war with Canada. In Chicago there already have been some disputes over how much water should be sucked out of Lake Michigan for distribution to the far suburbs. When we go to Chicago or New York we marvel how soft and good-tasting the tap water is. al


  7. I ticks me off to look over mountains north of here and see all sorts of rains falling somewhere, probably Queretaro. The “mountains” are not really that high, just hills really, and I don't see why they should impede the rains. Maybe we should blow up the tops of the mountains, like they do in the States for mining, and then rains would blow over our way, though the views might suffer a bit. Al


  8. We have two grease traps on the gray-water line coming out of the kitchen and the laundry, but we haven't really done anything to collect that water. Where the pipe ends there's a sort of oasis of greenery. I should think about that, though I've been told that gray water turns sour and smelly very quickly. The mulching idea is excellent. I will try that when the rains start. They sell bales of “rastrojo” which is like hay and very cheap. That would make excellent bedding material. Thanks. al


  9. Anonymous

    Water is never used up, it is only dirtied up and sent on its way. The real challenge is to use it as many times as possible. People on the reservation bathe, and then the water is used to mop the floor and eventually makes its way to someone's precious rose.Toilets use five gallons of water to flush away a cup of pee. Whiz outside and you save a lot of water.Robert GillPhoenix, AZ


  10. Peeing outside, eh? Must confess I've done that a few times when we return from town, reach the gate, but I'm not sure I can make it to a proper bathroom. I'll think about it though. We have people coming over for dinner on Thursday and I'll tell anyone who asks for the bathroom to head outside to a bush. I wonder how that'll go over. Thanks for the idea, Robert. LOL


  11. Anonymous

    My father used to say,” you drill the well first before you build the house, incase the water is crap”. We're country people, everyone has a well if there is good water in the ground. That is not always the case. “Someone tried to sink an unlicensed well about a kilometer from us, but after a month of much banging and belching by an ancient drilling rig, the project seems abandoned. No one knows if the water authorities shut it down, the owner ran out of money or they just didn't find any water.”It sounds like the people who tried to drill the well were using an old pounding drill rig . They have a bit of a problem with hard stone like granite, rotary rigs do a far better job. With the amount of rain you get a year, the distance you are from your neighbors, the amount of land you own, you would never deplete your water aquifer using what you use. Drilling a well with all the proper paperwork could be one of those “give back” type things, a tap at the gate that your poorer neighbors could use when they are flat out of water would be a godsend to your neighbors. Just sayin..


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