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riovista

Aug 12, 2013, 9:59 AM

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Cisterns

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We have 2 cisterns in the ground under the 'garage' and we have a black tank that holds water on the roof. Apparently from time to time the city pumps water to our house and it refills the cisterns. I'm told there is a float ball which stops the incoming water, although I have never opened a cistern to look. We also have separate pumps which bring the water from the cistern to the roof. When I remember I try to alternate which cistern I pull the water from.

Is that all there is to it ? Do I just wait for something to break and then fix it ? If we go away for six months do I just pick up where I left off ? Or are there chemicals (chlorine) which should be added from time to time. The thought of sitting water - even in a swimming pool - bothers me a little.



YucaLandia


Aug 12, 2013, 6:08 PM

Post #2 of 14 (26778 views)

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Re: [lhpdiver] Cisterns

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In an ideal world, there is no maintenance needed for your system. The real world is not ideal. The main issues arise from contamination of the water from potential:
~ leaks in the city water supply
~ leaks in the cistern
~ leaking around the lids/covers
~ accumulation of sediment/sarro (if the water is hard) ... or
~ parts failures like float valves that wear out (overfilling the cisterns or tinaco), pumps that oxidize (shaft seizure) or wiring/windings failures, plumbing problems, leaking pipes, a coflex hose leaking/failing at a toilet...

Fortunately, the likelihood of any single one of these things is low, which means one of them may occur every 3 to 5 years. Since these are all low frequency events, you can likely rely on full system checks just once every 6 months, and twice monthly(?) minor checks (walk through by a friend/neighbor) to make sure no leaks or overflowing water has occurred.

Leaks in the city water supply piping are very common and can result in soil microbes/bacteria entering your system, if there is insufficient residual chlorine in the water reaching your home. Standard disinfection of tinacos using normal bleach (no perfumes, no anti-spill gel-bleach), works out 10 mL per 100 L of stored water. For a typical 1100 liter tinaco/cistern (290 gal), you can add 110 mL of normal bleach => which conveniently equals 1/2 cup of bleach per typical black plastic Mexican 1100 L tinaco ~ as long as you have "clean" clear water ~ with no apparent TOC (Total Organic Carbon). If your water has suspended organic matter, (carbon), like old leaves or detritus or is cloudy, then remove the organic carbon source first, and then treat with bleach. Higher bleach concentrations are needed for suspended sediment laden (cloudy) water.

It is good to note that you likely should NOT add the bleach when you leave the property sitting unused.* Only add the bleach when you return, because when this level of bleach sits in metal pumps for long periods, it corrodes most pumps. When you return to use the house, add the bleach to the cistern you will use first and to the tinaco on the roof. At this concentration, it takes bleach 15 minutes of contact time to disinfect plumbing - as long as your system has visually clear/clean water without suspended sediment or organic carbon. To get your home plumbing system clean, mix the bleach well in the tinaco, wait 15 minutes, and then flush toilets and run faucets until you smell bleach in the water at each of these water outlet points.

This give you bleach-treated water with enough free chlorine to disinfect your pipes and faucets. Let the water system sit unused for 15 minutes with the bleach-treated water to completely disinfect the pipes - giving you clean water to use.

I know that some readers are shaking their heads at this advice (thinking it is unnecessary), but consider the research studies on typical Mexican city water systems. In the last big testing surveys on Merida's city water system (roughly 1 million users), 97% of the homes had clean, disinfected water at the meter at the street (entering the home). That number fell to only 75% with clean water at the kitchen tap/faucet on those same homes. This proved that 1/4 of the Merida homes had fecal coliform contamination inside the tinaco/pipes of their homes.... It also proved that even with good residual chlorine levels at the meter where the city water enters the house, the chlorine levels were NOT high enough to disinfect the homes that had contaminated plumbing/cisterns/tinacos between the meter and the kitchen sink...

This says => 1 in 4 Mexican homes likely have contamination inside the home plumbing... needing bleach disinfection.

*Note: If you have PVC plumbing on the roof - or PVC plumbing that is exposed to sunlight, these procedures are NOT enough. Since UV light penetrates PVC plumbing, algae grows inside the pipes wherever sunlight hits PVC (except for the new NO-GLUE "PVC-Plus" - pipes where you have to use thermal welding to bond the pipe-joints). When the PVC plumbing exposed to sunlight sits unused, the residual free chlorine levels fall in a week (no disinfectant ability left) and you start to have algae gardens growing inside the PVC tubing.**

Once the algae has grown thick, the best way to get rid of thick algae is to use high pressure water (from a pressure washer) to blast it out through an open spigot (to not clog faucets)... I have had to do this on 4 different friends homes - bleah.... This happens in Mexico (and not in Canada or the US very much) because the gravity feed systems used with common Mexican tinacos must have at least on tube to the city air for them to breathe - and algae spores float into the open breather tubes. ... *One way to limit the algae formation in sun-exposed PVC tubing would be to treat the water in the tinaco with bleach, mix it, wait 15 minutes, and then open enough faucets to flush and fill the sun-exposed PVC pipes with bleach-disinfectant-loaded water, and then moth-ball the system. (giving you hopefully sterile bleach-treated water standing inside the PVC pipes, but not in any pumps)

Good luck,
steve



**The algae garden inside sun-exposed PVC effect should be reduced by painting the PVC tubing black, or covering it with a UV blocking material. We also put a jelly-jar on top of each of the water system air vent tubes, where air still flows, but it makes a tortuous path for the algae spores to have to travel before they can enter the open air vent tube:



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GringoCArlos

Aug 12, 2013, 9:33 PM

Post #3 of 14 (26759 views)

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Re: [lhpdiver] Cisterns

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If you go away for 6 months or any length of time, turn off the water supply and pumps to the house. Should there be a leak on your side of the meter and no one sees or stops it, you could receive a water bill for tens of thousands of pesos.


YucaLandia


Aug 13, 2013, 6:42 AM

Post #4 of 14 (26733 views)

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Re: [GringoCArlos] Cisterns

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I really like this advice and perspective, but I am a bit confused on how it works.

Do you have a suggestion about how the gardener or caretaker can flush toilets and water the yard/plants, when everything is turned off? Do you also drain the tinacos, to prevent the possible floods?

If the tinacos are drained... then it makes it hard to water things or flush toilets etc. ???

(This is why we keep the tinacos full, and instead have a family member do a quick walk-through a few times a month.)

We have had 2 flexible lines going into sinks and toilets fail in the past 3 years - spewing water - so, I just change-out all the flexible lines at sinks and toilets. ???

Our city water bills are just $40 - $60 pesos a month, so, water rates are low - so the periodic walk-through system would keep bills from leaks fairly low, and concrete and tile construction, means none of the high costs of an unattended hose breaking in Canada or the USA. ???
steve
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(This post was edited by YucaLandia on Aug 13, 2013, 7:46 AM)


sparks


Aug 13, 2013, 7:39 AM

Post #5 of 14 (26720 views)

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Re: [GringoCArlos] Cisterns

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You should have a main shutoff from the street ... hopefully. My pump can freeze up or loose prime if not used for a long time so it's unplugged until I want to use it. An empty tinaco up 2-3 floors in wind storm is not a real good idea

Sparks Mexico Blog - Sparks Costalegre


AlanMexicali


Aug 13, 2013, 8:14 AM

Post #6 of 14 (26712 views)

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Re: [YucaLandia] Cisterns

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In Reply To
I really like this advice and perspective, but I am a bit confused on how it works.

Do you have a suggestion about how the gardener or caretaker can flush toilets and water the yard/plants, when everything is turned off? Do you also drain the tinacos, to prevent the possible floods?

If the tinacos are drained... then it makes it hard to water things or flush toilets etc. ???

(This is why we keep the tinacos full, and instead have a family member do a quick walk-through a few times a month.)

We have had 2 flexible lines going into sinks and toilets fail in the past 3 years - spewing water - so, I just change-out all the flexible lines at sinks and toilets. ???

Our city water bills are just $40 - $60 pesos a month, so, water rates are low - so the periodic walk-through system would keep bills from leaks fairly low, and concrete and tile construction, means none of the high costs of an unattended hose breaking in Canada or the USA. ???
steve


Here if you have an INAPAM card of pension card from somewhere you can apply and get a 50% discount on your municipal water bill.


GringoCArlos

Aug 13, 2013, 9:27 PM

Post #7 of 14 (26668 views)

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Re: [YucaLandia] Cisterns

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I'll give just two examples for my advice.

I had a water line break under the downstairs bathroom sink in the middle of the night. It ran for two hours until I woke up . Just sounded like a normal rain with the roof water running off until I checked and it wasn't raining outside.

That leak used 10 m3 of water. Not much, 80 pesos extra or so for those 2 hours, but about the same amount of water that I normally use in a month. If I hadn't woken up or been home, no one walking outside the house would have a clue to the leak because there is a floor drain in that bathroom.

A clueless friend had a leak from her tinaco on the roof and paid no attention to the bit of water running out of one roof spout in the back. Until she got a water bill the following month for 7000 pesos. That worked to get her attention. A copper joint in the water supply on the roof to the tinaco had failed. The water supplier refused to budge, and got their 7000 pesos.

If you have someone come in to check things while you're away, then it's just as easy for them to turn on the water supply out in front, flush the toilets, run the water in the sinks to fill the traps, etc and then shut off the water supply outside when they leave, until their next checkup.

For those with gardeners, they also can turn the main house supply on and off. Or keep a 55 gallon drum of rainwater for them to use for potted plants in your absence. Low water rates are no excuse to potentially waste thousands of liters of water.

A tinaco by itself does not deliver pressure at the same higher levels of city connected water. If the water supply to the tinaco is turned off, your potential losses are limited.


(This post was edited by GringoCArlos on Aug 13, 2013, 9:37 PM)


YucaLandia


Aug 14, 2013, 6:29 AM

Post #8 of 14 (26640 views)

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Re: [GringoCArlos] Cisterns

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I'll give just two examples for my advice.

I had a water line break under the downstairs bathroom sink in the middle of the night. It ran for two hours until I woke up . Just sounded like a normal rain with the roof water running off until I checked and it wasn't raining outside.

That leak used 10 m3 of water. Not much, 80 pesos extra or so for those 2 hours, but about the same amount of water that I normally use in a month. If I hadn't woken up or been home, no one walking outside the house would have a clue to the leak because there is a floor drain in that bathroom. ...

A tinaco by itself does not deliver pressure at the same higher levels of city connected water. If the water supply to the tinaco is turned off, your potential losses are limited.


That all makes sense. It's very cool that you have such good water pressure. Our city water pressure in Merida is generally so low that it barely goes above 10 ft to 12 ft in many neighborhoods, and it has very low flows even at ground level. We must use cisterns or ground level tinacos with pumps, or pumps connected directly to city water to push the water up to roof-top tinacos - and the tinaco provides all our pressurized water. This means that our tinacos provide much higher water pressure than City water. This also explains why you worry about leaks versus our quite low city water pressure - showing yet again how one person's experience in Mexico often has little bearing on other people's realities.
steve
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citlali

Sep 1, 2013, 6:16 PM

Post #9 of 14 (26246 views)

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Re: [YucaLandia] Cisterns

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We do not have a tinaco but we have an underground cistern, when we leave we turn off the pump so there is no water pressure. We have two lots so the gardner can water from the taps in the garden or get water in his bathroom but the water to the house is off- One day a hot water line busted and I turned off the pressure pump immediately so we did not have a big mess but I can imagine that water spewing off for several days if we were away until the cleaning lady came in and who knows if she would have known to turn off the pressure...


donemry

Sep 5, 2013, 7:46 AM

Post #10 of 14 (26166 views)

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Re: [YucaLandia] Cisterns

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Understand treating the cistern with bleach, but, by design, the water in the cistern is constantly being used and replenished. So, how often would you treat the water in the cistern. We have a 5,000 Liter cistern.


YucaLandia


Sep 5, 2013, 9:06 AM

Post #11 of 14 (26157 views)

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Re: [donemry] Cisterns

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It depends on the cistern and how much free chlorine the incoming water has.
Clean system + good free chlorine levels => treat it twice a year - and/or every time we have family/guests coming from Canada or USA.

How clean does your cistern stay? Rainwater/stormwater infiltration? Sediments - especially organic materials (leaves, etc) at the bottom?

A swimming pool chlorine test kit works to test your water coming in. Many (most?) Mexican cities have decent residual free chlorine levels provided at our taps. The last study of Merida city tap water found 97% of Merida homes had clean water with good residual levels of free chlorine at the meter - with enough chlorine to keep a well maintained home cistern in good shape.

The study also found that 25% of the Merida homes tested had microbial contamination inside the home plumbing, as shown by clean water at the meter, and microbially contaminated water at the kitchen sink.

Since I have no idea how good your water is at the meter (or well), and no idea how clean and "tight" your home's system is, I can only guess at how often to treat. A swimming pool test kit, or inexpensive water tests ( " Total coniforme (TC), coliforme fecal y E. coli estas pruebas en el agua " ) could be a good start.

If your system is clean, and you have a steady strong supply of clean chlorinated water, then I would think twice-a-year treatments would be sufficient. If your house's city water pressure is low or drops, then there may be leaks in the city's plumbing that allow contamination to enter, but if the water continues to have good free chlorine levels and your system stays visibly clean, then it's all good.
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donemry

Sep 5, 2013, 11:47 AM

Post #12 of 14 (26141 views)

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Re: [YucaLandia] Cisterns

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It is untreated water from a mountain stream/river. We don't drink it.


sparks


Sep 5, 2013, 2:12 PM

Post #13 of 14 (26130 views)

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Re: [donemry] Cisterns

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I treat the cistern and not the water and that was only when the tank needed cleaning. Since I put a double filter from the street the cistern stays mostly free of sediment. Mine is plastic with the top above ground level so no seepage or other contaminants. Ours is pure water from the street with no additives.

Sparks Mexico Blog - Sparks Costalegre


YucaLandia


Sep 5, 2013, 10:06 PM

Post #14 of 14 (26101 views)

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Re: [donemry] Cisterns

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Even though you don't drink it, I would keep the cistern clean and sediment free.

Are there any deer or wildlife living upstream of you? If so, then giardia becomes a possible issue. (Cryptosporidia is no fun.)

I would assume that as long as you use it as grey water: don't brush teeth, drink with it, get it in your eyes, don't wash dishes or do final rinses of dishes with it, then there would seem to be no need to disinfect your cistern water - as you would likely need to treat it constantly if you did not follow these precautions. The quality of stream water is notoriously variable, depending on rainfall rates upstream, ranching activities moving livestock in and out of the stream's drainage areas, etc., which means that any water tests you do now, likely would not apply to conditions even a month from now.

Due to the historically high frequency of worms and cryptosporids in people who use untreated water in Mexico, I would follow the typical Mexican physician's advice to treat yourself and anyone living there for parasites twice a year, including worms, amoeba, paramecia, and cryptosporids.
Hope you stay happy and healthy!
steve
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E-visit at http://yucalandia.com
 
 
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