By Matthew Baring-Gould, Kingscliff-based drainage plumber. Servicing Tweed Heads for 4 years. 5.0 stars across 173 Google reviews. Licensed NSW 383340C and QLD 15036450. ABN 74 605 392 348.
Drainage install at a Banora Point property to prep for a new rainwater tank. Fitted 2m of 150mm EvoMax channel grate across the slab where the tank would sit. Cut the existing slab to run a new tank overflow discharge. Built a small retaining wall. CCTV survey of the full stormwater system as a no-charge extra to confirm the receiving line was in good condition before the tank connected to it.
What the customer called us for
Owner called us out to install drainage around the pad where their new rainwater tank was going in. Needed a channel grate across the slab to catch overflow and spill water, and a new overflow line from the tank itself through the slab to the main stormwater.
What we found when we got there
The pad was ready for the tank but needed drainage prepared before the tank arrived. The slab had to be cut to run the overflow line through it. The existing stormwater system had never been checked, so before connecting the tank discharge into it we needed to know it could take the extra load.
Why we did it this way
Rainwater tank overflows get overlooked. The tank is sized for the catchment, the inlets work, the pump works, but when the tank is full the overflow has nowhere good to go. If you cheap out and daisy-chain the overflow into the existing stormwater without checking the receiving line, you find out the hard way (next big storm, water pooling at the base of the tank, no path out). Cutting a dedicated overflow through the slab is the right spec. The EvoMax channel grate across the slab catches any surface spill from the tank itself, so you have belt-and-braces drainage on the whole install.
What we did on site
- Built a small retaining wall to support the pad edge.
- Cut the existing concrete slab to run a new overflow line for the rainwater tank.
- Fitted 2m of 150mm EvoMax channel grate across the concrete slab where the tank will sit.
- Connected the new overflow and channel grate into the main stormwater line.
- Ran the CCTV camera through the full stormwater system to confirm the receiving line was in free-flowing condition.
- Documented every stage in photos for the owner.
The result
Pad is ready for the tank install. Overflow drainage built to spec through the slab. Channel grate across the slab catches surface spill. Stormwater system verified clean and free-flowing for the new load. Second visit to connect the tank itself will take an hour or two once the tanks arrive.
If you have the same issue
If you are installing a rainwater tank on your property on the Tweed coast or Gold Coast, do not skip the overflow drainage. Size the overflow larger than you think you need, run it to a working receiving line, and CCTV the receiving line first so you know what you are connecting into. Spending a bit more on the overflow saves you the next big storm. Call Matty on 0447 188 394 or request a quote.
Customer names and addresses have been withheld. Individual results vary. Drain Masters Plumbing is licensed in NSW (383340C) and QLD (15036450).
Frequently asked
Why cut the slab to run the overflow instead of running it around?
Running the overflow around the slab means long pipe runs with more bends and less fall. Cutting through the slab gives you a direct short path with full fall, which is what you want for an overflow carrying water under pressure during a storm event. Fewer bends means less chance of blockage, more pipe diameter available at the discharge.
What is a 150mm EvoMax channel grate?
A modular linear drainage system in a 150mm width. It sits flush in a slab, handles vehicle loading, and gives a clean architectural finish while catching surface water. We use it on garage frontages, pool surrounds, tank pads, anywhere water needs to be captured off a hard surface.
Why CCTV the stormwater before connecting a tank overflow?
If the receiving line is already compromised (roots, silt, broken joints) and you add a full-pressure tank overflow to it, the extra load exposes every weakness. Better to find out on a calm day with a camera than during a storm with water flooding your yard.
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