need to waterproof inside concrete watertank

Ricta

Hi all,
I need to refurbish an old underground water tank made of blocks and plastered. After filling in any cracks/holes in the plaster I will need to apply a waterproof coating. It's not used for drinking water.
I have seen products on the shelf, bitumen paint and damproof liquid membrane, Aquaseal and Thompson's, but I wonder how effective these would be. Bitumen paint would be good from a cost point of view.
I have also seen wonderful looking products on foreign websites (Liquid Rubber in U.S, and others in Australia/Newzealand) but do not think these are distributed in Ireland.
Can anybody recommend a product? There's about 26 sq. M. to be done, and cost is a consideration of course.

regards and thanks

DOCARCH

I'd suggest GRP/fibreglass as your best bet.

Ricta

DOCARCH wrote: »

I'd suggest GRP/fibreglass as your best bet.

that certainly would be a good way to go, but I think it migh tbe outside my DIY range and may be expensive?

But you have made me think laterally about lining the tank, eg polythene dpm jointed with double-sided bituminous tape between 200mm overlaps and polythene jointing tape over the edges.
The top edge of the dpm would be above the overflow pipe.
I wonder if I could use the bituminous tape to stick the polythene to concrete around the top of the tank, and around the overflow outlet.
I would end up with a polythene bag inside the tank!

or am I off my head!

mickdw

Is there likely to be any inward pressure from groundwater? If there is and if the tank water level goes low from time to time, the external water will push inwards and would destroy the polythene lining.

If there is no great inward water movement, something like a bituthene membrane might be an idea.

Carlow52

if using any chemicals in the tank for water proofing, ensure adequate ventilation during application

Joey the lips

It will all depend whats being stored in the tank. If its only water then it will deped on what the water is being used for also.

Protim use to do a rubberised concrete sealer you paint on with a brush. This stuff was great. It water sealed the gables of poorly sealed houses for years.

I say use to because protim is gone but if you google protim products you will get the new agent.

Ricta

While browseing for products I came across a Co. Clare company who are Specialist Paint Suppliers and Surface Coating Contractors. They responded to an email query suggesting a product called Nitocote CM210.
To put two coats on my 26sq.M. will take €500 worth of this product. We don't know yet how our future water charges will be structured around use, but I'm sure there would be a good return on investment.
Before we had a group water sheme, this tank was the only source of water for 2 adults and 3 children for many years, and it met our demand for for the majority of the year, needing to buy a tanker of water maybe once a year.
I've been searching to see what farmers are paying today to see if I could work out some figures around that, anybody know how farmers are charged?
I already have a meter installed and can work out usage while the underground tank is out of use for a couple of weeks.

BR

Damoh

Just wondering if you actually used the Nitocote CM210? did it work for you?
I have a cast concrete 3 tier fountain, the bottom tier(or bun) is made up of 4 segments joined together. However it leaks!
Can you advise me on a product that would allow me tocoat the inside of the concrete bun to waterproof it and plug these smallhairline cracks?
Regards
D

lowkeys

Look up the grace products website or give them a call. I have used their products before and found them expensive but they do work.

landcrzr

Try a company called IBC, they have numerous water proofing products, a paint on type will probably suit you best.

Ricta

In the end, I didn't coat the inside of the tank. I drained and cleaned it, filled a couple of holes with cement and then waited a few days. It was a wet time of year (when wasn't!) and the condensation on the walls would just not dry out, a dry surface was needed. So I let it fill up again. The concrete plug seems to be doing the job.