Forums > Specific Focus > Home, Garden & Construction in Mexico

robt65

Feb 8, 2012, 5:47 AM

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Just a "Tip"

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I found out today that many of the NOB commercial water faucets with a single "mixing valve" may not work well at all, and in fact reduce the volume of water in a home in Mexico down to a small dribble, especially a single story home without the advantage of additional height for "free fall" water pressure! This appears to be based on the fact that water pressure here in Mexico is not usually sufficient to operate the mixing valves efficiently.

After I bought all good quality (Delta, etc.), manufactured shower heads, and sink units NOB for our remodel, I had to change them out to cheap Mexican unit, until I get our in ground cistern and filter / water pressure pump installed. I sure didn't figure on that one! (smiling) The cheaper ($245 MX Peso) units work just fine for now.

So this is just a "heads up" for those who may be planning the same retrofits, I have done.

robt65

Papirex

Feb 8, 2012, 11:20 AM

Post #2 of 10 (6543 views)

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Re: [robt65] Just a "Tip"

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It must be known that a gravity fed water system only generates slightly less than one half pound of pressure for every foot of elevation to the water source, the rooftop tinaco here. That pressure is reduced by every foot that the piping rises.

I guesstimate that we only have about ten pounds of pressure at our downstairs kitchen , and the wash basin in the downstairs half-bath here, and about two pounds of pressure at the upstairs shower heads. It takes about ten or fifteen minutes for our outside automatic clothes washer to fill.

The only way to get higher pressure here usually is to pay for having an electric water pressure pump to be installed, not the electric pump that pumps the water from your cisterna to the tinaco on the roof. You will probably only get about 30 pounds of water pressure if you do that.

I was at one time a licensed plumber in the United States. 30 psi is considered to be low pressure up there. 60 psi is considered to be good. Do not depend on a clerk in a hardware store, or a plumbing supply house to tell you if something will work, they are probably guessing.

I have yet to find a fully qualified plumber or electrician in México. There is no personal licensing here. Their idea of an apprenticeship is to just do the work, My own five year apprentice ship was five years of working under the direct supervision of a licensed journeyman, plus we had to go to night school two nights per week, for 4 hours every night.

We studied all of the applicable laws of physics, Basic electricity, mechanical drawing, etc. To prepare to take our state examination to become a qualified journeyman at the end of five years. These were university courses, graded by the local college. No degree was earned, but they were university courses.

Correct plumbing is not as simple as most people think it is. An untrained plumber can kill you, your family, and many of your neighbors just as dead as any electrician can. Ever seen the results of a water heater explosion? A 30 gallon water heater will explode with the force of one pound of TNT. The force of the explosion dissipates in inverse ratio to the distance traveled. At one foot, it only has the force of ½ of a pound of TNT, etc, etc. etc. It will still have enough energy to level the average house, and kill everyone in it.

Be very, very careful when working on your own house, you don't want to create a death trap.

Rex
"The supreme happiness of life is the conviction that we are loved" - Victor Hugo

YucaLandia

Feb 9, 2012, 7:01 AM

Post #3 of 10 (6499 views)

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Re: [Papirex] Just a "Tip"

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Hi Papirex,
Just as Robert found out, bringing US ways of doing things to Mexico doesn't always work - or said another way: Mexicans do sometimes know what they are doing. You propose 60 psi as the standard, while Mexican pressure systems are typically set up at lower values: between 20 - 35 psi. e.g. If you buy a pump here, without a pressure switch, the common pressure switch sold here in Yucatan operates at 24 psi.

I've only set up 4 hidroneumaticos, and only worked on another 3 systems with them, but very consistently we've found that when installing a hydropneumatico on an existing tinaco gravity feed system: typical Mexican plumbing materials, joints, and connections leak significantly if you pressurize them to more than 35 - 40 psi. When retrofitting tinaco-gravity-feed systems with pressure pumps, the leaks have occurred under floors, inside walls, and in places that were difficult to access and required some demolition of pretty one-of-a-kind tile etc.

Given the potential for leaks, demolitions, and repairs, it just is not worth it to try to crank up the pressures to 60 psi US municipal standards, and instead we find it better to default to US rural home-well conditions of 30 psi or less. Our customers have found that a range of 20 psi - 30 psi meets most of their needs without creating leaks. This is enough pressure to fill a washing machine fairly rapidly, and provides reasonable shower pressures.

If you buy a hidroneumatico here in Mexico, we also recommend using the 2 adjusting nuts to get approximately a 4 psi working range of pressure under 30 or 35 psi - and adjust the air pressure in the bladder/diaphragm to within 2 psi of your lowest pressure. e.g. if you have a working range of 25 psi when the pump kicks-in and pump shut-off at 30 psi, then adjust the air pressure in the bladder/diaphragm to 23 - 25 psi. ** Hint: We've found most Mexican plumbers do not know how to make these adjustments.

Overall, I very much agree with Papirex's advice, but there are many instances where good NOB theory doesn't fit Mexican realities.
steve
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(This post was edited by YucaLandia on Feb 9, 2012, 7:07 AM)

YucaLandia

Feb 9, 2012, 7:03 AM

Post #4 of 10 (6498 views)

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Re: [YucaLandia] Just a "Tip"

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Continuing with the "Tip" theme of this thread...

**More practical sidelights:
~ We have at least one species of ants here that like the sparking etc that occurs when the electrical contacts open and close in the pressure switch. As a result, the ants climb into the switches - and get roasted in the contacts. After a number of them burn in the contacts, it interrupts the contacts and the switch stops working. On a typical Mexican hidroneumatico, the switch actually only uses one of the pairs of contacts (to switch the 127V hot line), while the switch contains 2 pairs of contacts. This allows the repairman to move the hot lead from the burned contacts - over to the previously unused fresh set of contacts. If your previous plumber switched both hot and neutral by connecting both black and white wires, then you need to file/sand/polish/clean both sets of contacts.

~ To keep the ants from returning, I have found that we must put down a solid trail/ring of ant powder (insecticide powder) around the mounting feet of the hidroneumatico, around the base of the pump platform, and around the feet of the motor, which blocks future ant paths to the pressure switch - otherwise they reliably return and take out the pump repeatedly.

~ It is also worth noting that some hidropneumaticos sold in Mexico use cheap colorless plastic tubing (roughly 1/4 inch diameter) to connect between the pump head and the pressure switch. This tubing is not designed to be in sunlight, and typically fails in less than a year. There is a better grade of plastic tubing (brown colored here) that is designed for exterior usage, that lasts at least 5 years - or install a piece of copper tubing for a near permanent fix.

Hope you enjoy the fruits of other people's experiences,
steve
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chicois8

Feb 9, 2012, 4:30 PM

Post #5 of 10 (6452 views)

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Re: [robt65] Just a "Tip"

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I wonder how many faucets bought in Mexico still have lead in them, every time I see a plumber working in Mexico I pick up his solder and every time it has been 50/50 ( 50% lead and %05 tin) which has been out lawed in the US for a number of years.............

YucaLandia

Feb 9, 2012, 6:40 PM

Post #6 of 10 (6440 views)

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Re: [chicois8] Just a "Tip"

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The issue of lead in water leaching from lead soldered joints comes primarily from basic (alkaline) hard water that has been standing in the pipe overnight or longer. If you are drinking tap water, whether here in Mexico or in Canada or the United States, it is best to flush the drinking water line first thing in the morning. Since a typical toilet flush draws between 1.6 - 5 gallons, flushing a toilet on that part of a house's plumbing, also flushes out the lead that accumulated overnight.

100 feet of normal 1/2 inch pipe only holds about 2 gallons of water. This means that a single toilet flush in the morning easily removes the accumulated lead from that circuit. If you have very large 3/4 inch pipes, (unusual), then every 22 feet of pipe holds 1 gallon. If there is 50 feet of normal 1/2 in. tubing between your tinaco and your kitchen sink, (a typical run of pipe) then running 1 gal. of water through the faucet flushes out the lead. If your faucet has modest flow, then it typically takes a minute of rinsing dishes, etc to flush the line before drinking.

Since the average American uses over 500 gal of water a day, the issue of lead accumulating in drinking water from lead soldered joints really is quite minimal. Mexicans use about 375 gal of water per day per person, so, even with Mexican levels of water usage, lead from drinking tap water is not a significant risk. http://www.data360.org/...ata_Set_Group_Id=757

There has been some evidence that basic (alkaline) water sitting overnight (or more than 6 hours) in chilled-water drinking fountains may have elevated lead levels from all the soldered joints in the refrigeration plumbing. The solution to this is to run the drinking fountain for a minute after it has sat unused overnight.

Our significant lead exposures actually come from typical fishing (handling and biting lead sinkers/weights), from lead in soil and dust, and lead-based paints in older constructions. For comparison purposes, the typical risks from lead in home drinking water are quite low: The health risks from breathing soot particles from passing buses, radiation exposure from airplane flights, second hand smoke from tobacco smokers, from radon exposure, from living at altitudes over 5,000 feet, and regular exposure to sunshine, each pose greater health risks for most people than lead in drinking water. The PNAs from grilling a hamburger or steak also represent greater health hazards than typical lead levels in drinking water. The toluene that bleeds out of common construction adhesives presents greater health risks than typical lead levels in home drinking water. Breathing the THMs present in chlorinated US drinking water during a typical shower presents greater health risks than typical lead lead levels in home drinking water.

If your house has (very old) lead pipes, then all of the above descriptions of health risks do not apply.
Dr. Steven Fry
Ph.D. in Public Health and Environmental Chemisty
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(This post was edited by Rolly on Feb 11, 2012, 12:23 PM)

chicois8

Feb 9, 2012, 7:11 PM

Post #7 of 10 (6432 views)

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Re: [YucaLandia] Just a "Tip"

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Steve, what if first thing in the morn a gallon or 2 are put into a pot for beans to cook, the cook thinking the boiling water will kill bacteria but what happens to the lead, does it boil off or does it concentrate as water boils off?

robt65

Feb 9, 2012, 7:32 PM

Post #8 of 10 (6432 views)

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Re: [chicois8] Just a "Tip"

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Hi chicois8,

I can't venture a guess on that one, but I can tell you there are no cast or steel or galvanized pipes on this property. I went all copper (boy that's an expense especially for 3/4 sections of copper tubing) and I brought about six rolls of solder from the USA. No lead in our house pipes. Even the JAPAM pipes on the street appear to have all copper tubing in them. Now what JAPAM has used for solder, I cannot tell you. But thanks for the thought.

robt65

YucaLandia

Feb 10, 2012, 6:09 AM

Post #9 of 10 (6411 views)

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Re: [chicois8] Just a "Tip"

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Chicois,
You're thinking clearly. Cooking beans in water drawn first in the morning:
Since we do not boil the beans to dryness, the concentration effects are smaller. Still, since the initially-dry beans absorb a lot of water, they absorb lead with the water...

Ingested lead is stored in fatty tissues like liver, brain, marrow, etc - and lead also deposits in bones. Our bodies absorb the lead we eat, and they eliminate ingested lead very very slowly, through fingernail and hair growth, so, once consumed, we tend to accumulate lead over time. This is a major reason why we want to avoid ingesting lead and other heavy metals - in addition to cognitive losses, neural system problems, etc. (No biting fishing weights to crimp them - and no licking your fingers after handling lead fishing weights.)

Because the beans absorb so much water, it really would not be a good thing to daily eat beans cooked in the first draw of water every morning from copper plumbing. See the next reply for "The rest of the story".

Robt65,
Past and current US EPA drinking water rules and ANSI/NSF Standard 61: Drinking Water System Components allow up to 8% lead in plumbing fixtures, so, most people imagine that they have no lead exposure, by buying copper piping and modern fixtures. If you have alkaline tap water, the same rule applies: flush your drinking water lines EVERY MORNING before drinking or cooking with that water, due to lead in what we imagine to be lead-free fixtures. Also flush lines if they sit with alkaline (or acidic) water for over 6 hours.

Since basically all metal faucets have some lead leaching out after sitting unused for 6 hours, it is important to gently flush them before drawing drinking water. Running water for 5-10 sec typically flushes most fixtures. This is especially true if you have young children drinking the water - or eating foods cooked in such water (especially foods that absorb water like dry beans).

Children's brain development is definitely harmed by even small lead exposures - and it really is a minor thing to develop a habit of running the tap briefly before drawing drinking or cooking water.
Dr. Steven Fry
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robt65

Feb 10, 2012, 9:14 AM

Post #10 of 10 (6385 views)

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Re: [Papirex] Just a "Tip"

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Hi Rex and Steve,

Thanks to both of you for some good reminders. Rex . . . . . My plans are to have a 10,000 liter cistern with a double filter system plus a pump to move the water to the pressure system, which has a 20 gallon pressure tank, a dual 30 / 50 pressure switch. The system such as shown here, ( http://stores.nextag.com/store/4886497/product/970970717/1-2HP-SHALLOW-JET) or here, (http://www.tractorsupply.com/shur-dri-reg-1-2-hp-tank-mounted-jet-system-3123522) worked well for me for many years for my house in the country with three bathrooms and a laundry room. If placed in a proper location they are easy to maintain and any repairs or replacement parts needed over the years are easy to make. I plan on using a one HP pump with a 20 gal pre charged tank and a 30 / 50 pressure switch. I will be coupling that to a Rotoplas in ground 10,000 liter tank with a double filter system. All piping to the house will be PVC. It is a typical country water well system and tank that works very well and a softener unit can easily be added if so wished.

Steve, I was indeed going to go for a 65 to 75 psi system, but again you reminded me where I was, and the very real possibility there may be a pipe lurking in these concrete walls I did not come across when replacing the 30 year old original copper water pipes. All I need is to have a pipe leak that went unseen or was neglected inside a concrete wall or floor somewhere. Your tip on using a less psi system is appreciated.

robt65