STOP A CONCRETE TANK LEAKING, WITHOUT REBUILDING IT

What fails in a concrete tank

Concrete tanks fail from movement, not from wear. The wall and base flex with ground movement, heat and the weight of the water. That opens hairline cracks at the wall to base joint first, then up the wall.

Common causes we find: - Ground movement and settling under the base - Tree roots lifting or splitting the base slab - Old render or bitumen coatings that have gone brittle and lifted - Rusted or slack bands letting the wall spread - Poorly sealed outlet and inlet penetrations

How the leak is diagnosed

We start with a drop test. You mark the water line and leave the tank alone for 24 hours with the outlets shut. A drop with no use points at the tank, not the plumbing.

On site we drain the tank, wash the inside face and look at the dry wall. Cracks show as damp lines that dry last. We also check the outside for wet patches, the bands for corrosion and the base for movement. If the wall itself has spread, bands are fixed before any liner goes in. There is no point lining a tank that is still moving.

How the repair is done

The tank is drained and cleaned back to sound concrete. Loose render, old coatings and sharp edges are removed. Any hole or step that would push through the liner is patched.

Geo-textile matting is fitted to the wall and base. It is a cushion. It keeps grit, cracks and rough concrete off the liner, which is what makes the difference between a liner that lasts fifteen years and one that fails in three.

The liner is then made to the tank diameter and height, dropped in, fitted to the wall and sealed at the top edge. Outlets, inlets and overflows are cut and clamped with sealed fittings. The tank is refilled and checked before we leave.

What it costs

Cost is driven by diameter first, then by access and the condition of the shell. A small rural concrete tank is the cheapest job we do in this category. A large diameter tank on a steep site with poor truck access is several times that.

See the indicative range below. Every job is quoted firm after inspection, and the written quote is the price you pay.

How long it takes

Most concrete tanks are lined in one to three days on site, once drained. Draining is the slow part and it is usually done by you before we arrive, so plan your water supply around it.

Metro jobs generally start within a week of you accepting the quote. Regional jobs are batched by area, so lead time depends on where you are. Ask when you call and we will give you a real date, not a guess.

What warranty applies

Workmanship is warranted by us. The liner material carries the manufacturer warranty for the grade supplied. Both are written on the quote before you accept, so you can read the terms while you are still deciding.

Warranty does not cover damage from things we told you to fix and you chose not to, such as roots left under the base or bands left slack.