BajaNomad

Cistern maintenance

weebray - 8-12-2015 at 04:59 PM

We need to repair some minor cracks and repaint a cement/ block cistern. We are looking for a recommendation for a waterproof, non-toxic, scrub able, coating that will by necessity need to stick to a surface that is at the very least very humid. Who out there has done this?

[Edited on 8-13-2015 by weebray]

Hook - 8-12-2015 at 05:02 PM

Can you drop a large enough Rotoplas tank into it? The best solution is plastic surrounded by the cement cistern. Much cleaner, too. Lasts longer., doesnt crack.

[Edited on 8-13-2015 by Hook]

weebray - 8-12-2015 at 05:08 PM

Good suggestion and we had considered it but dismissed the idea due to the reduction in volume. Your point is still valid though, we will measure the cistern and see if it is close in size to an available tinaco. We would probably have to add another tinaco on the roof for additional storage though. Water here in La Paz is muy rato and getting mas rato.

BajaGringo - 8-12-2015 at 05:27 PM

If you cannot drop a rotoplast into it, consider trying a fix I recently heard about. Someone with the same problem simply lined the inside of their pila with 6" cinder blocks, running a rebar line around every 3 rows to about a foot from the top, while also cementing them to the walls. The first row of blocks were perforated and he poured a new floor with mesh / rebar. He then filled the blocks with a very rich, wet slurry. He then finished it off to the top and then applied scratch and finish coats, the last coast troweling to a impermeable finish. The advantage of the cinder blocks is that they are more porous and absorb the slurry fill and scratch coats much better, ultimately creating a stronger wall and watertight finish.

I guess he lost a small percentage of his total tank volume but this method has been working for him now for over 10 years since he applied the fix.

The guy who sells cinder blocks here locally in San Quintin blends in an additive that makes the porous blocks really water tight. They will hold water for a full 24 hours with no leakage. Much better than standard cement blocks which is what most pilas today were built with.

weebray - 8-12-2015 at 05:44 PM

Another good suggestion. There is a powdered impermeabilizante that we sometimes add to cement when a waterproof wall is desired. This existing cistern has some visible cracks but is not losing water at an appreciable rate. I guess I'll wander down to Comex and see what they recommend for a coating. I guess we're most concerned with the toxic aspect. New walls would be overkill me thinks.

KaceyJ - 8-12-2015 at 08:06 PM

Are you really going to drink the water that is stored in your pila?

I think most don't, so since everything is toxic why not figure out wht the best coating would be and not worry about it?

We've used a product called Farbertite for years on all our steel storage tanks . Has a residual odor at first that goes away , is easy to apply , dries fast , and seems to protect metal real well .

Don't know about cinder block application though.

I'm thinking perhaps a flexible polyurethane coating.

surfhat - 8-13-2015 at 07:14 AM

Twenty years ago on the East Cape, I lined my underground block tanks with a two part epoxy product that was especially designed to store drinking water, as recommended by some organization NSF. Sanitation something or the other. It came in five gallon buckets, Part A and Part B. It was not cheap at the time, around $50/gallon but was the best product for storing drinking water I could find. I bought it at a local paint store here. Vista Paint seems to ring a bell. Never leaked and if one wanted to clean up a tank for any reason, it was easy as nothing would stick to the cured epoxy. I am not a fan of plastic liners unless it is well filtered to remove the taste, if that is even possible.

monoloco - 8-13-2015 at 08:27 AM

Hydraulic cement
http://construction.about.com/od/Thermal-And-Moisture-Protec...

Or, you can open up the cracks a bit with a diamond masonry wheel on a grinder, then fill them with polyurethane caulking. Polyurethane will adhere very well to concrete and remains flexible. Paint like coatings can prevent water leaking due to a porous material, but are ineffective at filling gaps.

Coating

bajaguy - 8-13-2015 at 08:27 AM

Any epoxy coating that has an NSF (National Sanitation Foundation) rating for potable water should suffice

MMc - 8-13-2015 at 09:12 AM

Mono, cool info thanks.
All my pilas have been plactic, so back to the thread.

mtgoat666 - 8-13-2015 at 09:23 AM

Quote: Originally posted by weebray  
We need to repair some minor cracks and repaint a cement/ block cistern. We are looking for a recommendation for a waterproof, non-toxic, scrub able, coating that will by necessity need to stick to a surface that is at the very least very humid. Who out there has done this?

[Edited on 8-13-2015 by weebray]


You need to determine if cracks are insignificant shrinkage cracks or thru-cracks. Fill tank with water, measure water level drop over 24 hours. If you lose water its a bad crack. Repair or replace. No water loss, no problem.

You can coat inside with a product specifically for water tanks. Probably an epoxy system coating. Inquire with a paint mfg like PPG.

Lorenzo - 8-13-2015 at 09:48 AM

As owner / operator of Campo Lorenzo in San Quintin we have gone through such a process a few times over the past 30 years and again last month. There are a lot of new products out that do a great job (plastic type paint, hydraulic cement, etc.) sealing cement. However, this year my 8,000 gal. above ground block/cement storage was beyond repair. The cost of a polyethylene tank costs around a dollar per gallon here in San Quintin which, I felt, was way too expensive. I located a manufacturer of these tanks in Temecula California and purchased a 5000 gal tank for only $1700.00 tax included USD and hauled it down on my trailer - total cost about $2500.00. Knowing what I know now, I could have saved almost 1/2 the money on crossing the boarder, but I still saved a bunch of cash. E-Mail me at campolorenzo@hotmail.com or SKYPE phone (909) 581-4140 if you want details. lorenzo

weebray - 8-13-2015 at 06:00 PM

The two foot opening to the cistern pretty much rules out a plastic tank without major construction/destruction to the garage floor. As directed we checked the at rest level of the tank over a 24 hr. period. There was an insignificant drop. El Arco (plumbing supply) in La Paz has a paint designed for pools. At about 800 pesos/gal. we plan to put on two coats. PPG has an outlet here but they are virtually closed as the road to their business is torn up and will be for ?????? Before painting we plan to grind out any cracks and fill them with ______? Who can fill in the blank? I'm aware that good enough usually isn't but in this case the tank ain't broke so.......... Excellent responses by all - thanks.

Bob and Susan - 8-13-2015 at 06:06 PM

do not waste your money on pool paint...
it chalks
you don't want that stuff in your water system

DO NOT paint it

repair it ...then...use pool stucco
cement does not hold water no matter what anyone tells you

monoloco - 8-14-2015 at 08:51 AM

I agree with Bob, don't waste your time with paint. The only thing you'll accomplish is poisoning yourself with the fumes.

23S52N - 8-14-2015 at 10:52 AM

A good friend of mine in La Paz does cistern and tank maintenance and cleaning. If you want to call him, Eduardo Morfin, cell is 612-140-1181. he is fluent in Spanish and English

[Edited on 8-14-2015 by 23S52N]

wessongroup - 8-14-2015 at 11:51 AM

Might wanted to look at "liners" ... they come in all sizes

http://www.carsonliners.com/liners/

La Paz water

captkw - 8-15-2015 at 10:06 PM

weebray,, its only gonna get worse (The water) the resivor is called "good women res/lake" and it on the road to La ventanna...La Paz is growing to large and fast. and water is a bad issue...

dtbushpilot - 8-15-2015 at 10:21 PM

My builder used waterproof stucco and an impermablazante coating but I had him tile the cistern with ceramic tile afterwards so that I would have a smooth surface to clean if necessary. Seems to be working.

weebray - 8-17-2015 at 06:19 PM

FYI Comex sells an epoxy with a nsf61 potable water rating. Close inspection of the cistern shows no serious cracks. A two gallon "kit" inc. a gallon of solvent is 3300 pesos. We plan to leave the cistern to dry out for two weeks then apply 1 coat in the corners and over any cracks or blemishes. We will follow the next day with un otro mano to 6" above the waterline.

Martyman - 8-21-2015 at 03:30 PM

We had our tank "stuccoed" about 5 years ago. It still leaks a little but there is always water left in it when we return after not occupying our shack for 6-8 months. Not perfect but it works.
I checked out a made to fit liner and it was way too expensive.

woody with a view - 8-21-2015 at 04:27 PM

FWIW, stucco is not waterproof. it's the paper underneath that keeps the water out of a house.