Stormwater
Stormwater & Outside Drains
Gully traps and sumps, who owns which pipe, the rules for stormwater, and when an outside drain needs a professional.
DIY
To unblock an outside drain, check whether it is a stormwater sump or a gully trap on the wastewater line, because that changes the risks. Put on gloves, lift the grate, scoop out the leaves, silt and debris, then flush with a garden hose. If the water still will not go down, drain rods pushed in and turned clockwise usually shift a blockage near the access point. If it is sewage, it keeps coming back, or it is out of reach, stop.
This guide covers the do-it-yourself part. For how outside drains are laid out, who owns which pipe and what the rules say, see our page on stormwater and outside drains.
Look at what is in it. Rainwater, leaves and mud mean a stormwater sump, downpipe or channel drain, and it is generally a clean-ish job. Grey water, food scraps or toilet paper mean a gully trap on the wastewater line, and you are handling sewage. Both can be cleared at the grate, but a wastewater gully needs more care with hygiene and less enthusiasm with water.
Whatever it is, wear rubber gloves and eye protection, keep your face away from the opening, and wash your hands well afterwards. Do not lift a manhole lid, or a grate on the street or berm. Those belong to Auckland Council or Watercare.
Most outside blockages sit within arm's reach of the grate, so start there. Lift the grate with a screwdriver or a gloved hand, scoop out the leaves, silt and debris with a trowel or an old cup, and bag it for the rubbish rather than tipping it on the garden next to the drain. Then look at the water level. If it starts to drop, you have found the blockage.
On a stormwater sump, keep going to the bottom. The silt that settles below the outlet is meant to be emptied, and a sump full of it sends everything straight into the pipe. On a gully trap, clear the dish and the top of the trap, but don't push anything down the outlet.
Once the grate area is clear, run a garden hose into the drain on full flow for a minute or two. Water that drains away freely means the pipe beyond is clear. Water that rises again means the blockage is further down the line. A garden hose will move loose leaves and soft silt. It will not shift roots, packed mud or anything solid.
Hardware stores sell drain-cleaning nozzles for garden hoses, which push water backwards out of the nozzle so it pulls itself along the pipe. They can help on a short run of silted stormwater pipe. On a gully trap, use the hose sparingly: if the line is blocked, every litre you add has to come back up somewhere.
A pressure-washer drain-jetting attachment is a small version of what a drainlayer uses, and on a silted stormwater pipe it can work well. The cautions are real, though:
Drain rods are flexible sections that screw together, with a plunger or corkscrew head on the end. Feed them into the drain from the access point, adding sections as you go, and push and pull against the blockage. Turn them clockwise only. Turning anticlockwise can unscrew the joints and leave a section stuck in the pipe, which turns a blockage into a bigger job.
Work gently. You are trying to break up the blockage, not force it. If the rods meet something hard that does not give, or you feel them catch on an edge, stop. That is often a root mass, a dropped joint or a broken pipe, and more force will not help.
Without rods you are limited to what you can reach and what water can move. Scoop out everything you can, flush with a hose or a hose drain nozzle, and try a wet-and-dry vacuum on standing water and silt in a sump. A large drain plunger over the outlet of a gully can sometimes shift a soft blockage near the trap. If none of that moves it, the blockage is beyond DIY reach.
Avoid improvised tools such as wire coat hangers, garden canes or lengths of hose pushed in by hand. They snap, get stuck, and add to the blockage.
Not really, and it is worth being honest about it. Hot water, baking soda and vinegar can loosen a thin film of soap or grease inside a house. Outside drains block with leaves, silt, mud and roots, which are solid material that has to be removed physically. No home remedy dissolves a pipe full of mud or cuts a root. Scooping, flushing and rodding are the natural method.
Chemical drain cleaners have the same problem: they are made for hair, soap and grease, not silt or roots. Never pour them into a stormwater drain, because Auckland's stormwater flows to streams and the sea untreated. On a gully trap, follow the label exactly and never mix products. If a drain cleaner is swallowed or splashed in the eyes, call the National Poisons Centre on 0800 764 766. For indoor drains, our guide on how to unblock a drain covers which home remedies are worth trying.
If the gully is overflowing with sewage, stop using water inside the house straight away, including toilets, showers, the washing machine and the dishwasher. If wastewater is also coming up in the street, at a manhole or at the neighbours', call Watercare on 09 442 2222 and press 1 before anyone else. Keep children and pets away from the overflow.
Don't hose the overflow into a stormwater sump or the garden. Stormwater is not treated, so that moves the sewage into a stream. Once the drain is clear, scoop up solids, wash hard surfaces with hot soapy water, and wash your hands and boots well. If only your property is affected and you can't clear it from the gully, it is a private blockage in the wastewater line and a job for a drainlayer.
Flushing water into a blocked wastewater line raises the level until it comes up somewhere else, often inside. Stop using water and get it cleared from the outside.
Stop when the blockage is beyond the first access point, when rods hit something solid, when the same drain blocks again within weeks or months, or when sewage is overflowing and won't go down. At that point it needs proper equipment, not more effort. Repeat blockages almost always have a physical cause, such as roots, a broken section or a sag, that clearing alone won't fix.
Your hands, a scoop and a hose, then drain rods. Outside drains block with leaves, silt, mud and roots, which have to be physically removed. Chemical unblockers are made for hair, soap and grease and do little to silt or roots, and they should never go into a stormwater drain. If rods won't shift it, the line needs jetting.
Not down a stormwater drain. Auckland's stormwater flows to streams and the sea untreated, so bleach goes straight into a waterway. In a gully trap on the wastewater line, a normal household amount used as the label directs is fine for smells, but it won't clear a blockage. Never mix bleach with other cleaners, because some combinations release toxic gas.
Scoop out as much as you can from the sump or grate first, then flush with a hose and keep scooping as the silt lifts. A wet-and-dry vacuum helps on a sump. If mud has packed the pipe itself, rods tend to pass straight through it, and jetting is what removes it. Find where the mud comes from too, such as bare soil or a broken grate.
Because the outside drain and the toilet may be on different lines. A blocked stormwater sump has nothing to do with the toilet. A gully trap that is blocked while the toilet flushes normally usually means the blockage is in the short pipe or trap serving the kitchen, laundry or bathroom waste, upstream of where the toilet joins the line.
Yes, although outside drains are drainlayers' territory. Clearing a blockage through an existing access point doesn't need a building consent, and restricted drainage work is done by PGDB-licensed drainlayers, who you can check on the public register at pgdb.co.nz. A drainlayer will have rods, a jetter and usually a camera, which covers most outside blockages in one visit.
It can be, with care, at the gully grate only. Wear gloves and eye protection, keep your face away, don't hose sewage into the garden or a stormwater drain, and wash thoroughly afterwards. If the overflow is large, keeps rising, or is coming up inside the house, stop using water and get it cleared rather than handling it yourself.
Tell us what it is doing and we will tell you what it probably is, what it takes to fix, and what that should cost.