When Your Stormwater Drain Floods

Newcastle gets its share of heavy downpours, and an East Coast Low can dump a month of rain in a day. When a blocked stormwater drain cannot cope, the water has nowhere to go but across the yard, under the house, or into the garage. Here is what causes stormwater drains to flood and what you can do about it.

Stormwater is not the same as sewer

It is worth knowing the difference. Your sewer carries waste from toilets, sinks and showers to the main sewer line. Your stormwater system is completely separate, it carries rainwater from your roof, gutters and yard out to the street drain or a soak well. They never mix. So a flooding stormwater drain is a rainwater problem, not a sewage one, though both can block for similar reasons.

Why stormwater drains flood

• Leaves and debris. The big one. Gum leaves, bark and silt wash into the grates and pits and clog them, especially after a dry spell followed by heavy rain.
• Blocked gutters and downpipes, so the water backs up before it even reaches the underground drain.
• Silt and sediment building up in the pipe over years.
• Tree roots, same as in sewer lines, getting into the joints.
• Undersized or old systems that simply cannot handle a big Newcastle storm.

What you can safely do

• Clear the grates. Rake the leaves and debris off the surface grates and pits so water can get in.
• Clean your gutters and downpipes before storm season, this prevents a lot of overflow.
• Check the outlet where your stormwater meets the street, if it is buried under leaves, clear it.

What to leave alone: do not pour chemicals down a stormwater drain, it runs straight to the creeks and the harbour. And do not go poking around in a flooded pit during a storm.

When to call

If you have cleared the grates and gutters and the drain still floods, or it backs up every time it rains, the blockage is underground in the pipe. That needs a high-pressure jetter to clear the silt and roots, and often a camera to find why it keeps happening. If you are in Newcastle and your yard turns into a pond every storm, give us a call and we will get it draining again.