How to repair a broken stormwater pipe

Fixing a broken stormwater pipe

A broken stormwater pipe is one of those things that sneaks up on you, because the pipe is buried and you never see the crack, you only see the symptom, which is usually a patch of lawn that stays soggy for a week after the rain has stopped. The good part is that a straight run of PVC stormwater is about the most forgiving thing you will ever repair, and it is a job plenty of people here do themselves on a Saturday with a shovel and a hacksaw.

How to tell the pipe is actually broken

• Soggy patches or pooled water in the yard that do not dry out after a few clear days.
• Slow drainage, or water backing up out of the downpipe in heavy rain.
• Visible cracks or splits where the pipe runs above ground or comes out of a wall.
• A sunken line running across the lawn, which is soil washing into the pipe through a break and settling.

That last one is the tell most people miss, and it is the useful one, because the dip in the grass usually sits right on top of the damage and saves you digging up half the yard looking for it.

What you will need

• A shovel, and a trenching shovel if the run is deep.
• A hacksaw, or a fine-tooth handsaw.
• Replacement pipe in the same size as what is in the ground, which is usually 75mm or 90mm.
• A slip coupling, sometimes called a repair coupling.
• Elbows, if your repair takes the run around a corner.
• PVC priming fluid, the red stuff.
• PVC solvent cement. Type N is the blue one and it is what you want for non-pressure work like stormwater. The green Type P is for pressure pipe, so leave that on the shelf.
• A tape measure, a marker and a clean rag.

Repairing the pipe

1. Dig it out

Take the soil away from the damaged section by hand near the pipe rather than driving the shovel straight down, because a shovel blade will happily turn a hairline crack into a proper break. Give yourself a good half metre of clear pipe either side so you have room to work and room to slide a coupling along.

2. Cut out the damaged section

Cut at least 100mm past the crack on each side, because PVC will often be stressed either side of the visible damage even where it has not split yet. Cut square, and take the burr off the cut ends with the rag or a blade, since a lump of swarf inside the joint is what stops it seating properly.

3. Dry fit before anything wet comes out

This is where the slip coupling earns its keep. It has no internal stop in the middle, so it slides all the way onto one pipe end, then back over the joint once the new piece is in place, which is the only way to join two fixed ends in a trench. Measure the gap, cut your new piece, and put the whole thing together dry first to check it lines up.

4. Prime and cement

Wipe both ends clean, brush the red priming fluid onto the pipe and into the socket, then the cement, then push and twist a quarter turn and hold it for a few seconds so it does not creep back out. Priming is the step everybody skips and it is the step that decides whether the joint holds, because the primer softens and cleans the surface so the cement can weld the two pieces together rather than just glue them.

5. Backfill

Check the tin for the cure time before you put any soil back, since it varies by product and by how cold the day is. Then backfill in layers and firm each one down gently rather than tipping the lot back in and stamping on it, which is how a fresh joint gets pulled apart.

Keeping it from happening again

• Check the exposed sections and the downpipe joints once a year.
• Keep the gutters clear, so grit and leaf litter are not washing straight down into the line.
• Keep vehicles and heavy loads off the ground above a buried run.
• Plant trees well away from the line, because roots will find a hairline crack and open it right up.

Shop related products

• Plumma's Blue Glue Type N PVC Solvent Cement, 250ml. The cement for non-pressure work like stormwater.
• Plumma's Red Priming Fluid PVC Pipe Primer, 250ml. Cleans and softens the PVC so the cement can bond.
• Supercraft Junior Hacksaw, Heavy Duty 150mm. Cuts PVC cleanly down in a trench where a big saw will not fit.
• Supercraft Hi-Vis Tape Measure, 8m. For measuring the gap twice before you cut anything.

Did you know we also stock the stormwater pipe and the fittings in the shop, in 75mm and 90mm, including slip couplings, elbows from 15 to 90 degrees, stepped adaptors, downpipe adaptors, grates and saddles, plus shovels and trenching shovels. They are not on the website, so give us a ring on (08) 8536 4333 to check what is on the shelf.

More of the plumbing range is at plumbing, and the saws and measuring gear are in hand tools.

A 6 metre length of stormwater pipe was never going to fit in the car, so if you would rather it turned up at the door, we deliver for $5 around Strathalbyn and $10 on the regional run. The days and the towns are on the local delivery page.

Keep reading

• How to choose a hacksaw and the right blade for the job
• Soudal T-Rex adhesive, what it sticks and when to use it
• What tools do you actually need in a home shed or workshop

I still dry fit the whole thing twice before the cement comes out, because solvent cement does not give you a second go at it, and I would rather look silly in my own backyard than dig the trench out again.

Candeece

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