Diagnosis
9 Signs of a Blocked Drain
Gurgling, slow drains, smells, a rising toilet — each symptom narrows down where the blockage is. Here is how to read them before you call anyone.
Prevention
The items that cause the most avoidable blocked drains in New Zealand homes are cooking fats and oils, wet wipes including those labelled flushable, sanitary products, coffee grounds, rice and pasta, cotton buds and dental floss, food scraps, and paint or building washings. Only three things should go down a toilet: urine, faeces and toilet paper. Everything else, including products marketed as flushable, should go in the bin.
Roughly speaking, blockages fall into two categories: those caused by the pipe failing, and those caused by what went down it. The first kind needs a drainlayer. The second kind is almost entirely preventable, and it is a large share of the callouts we attend.
| Item | What it does | Instead |
|---|---|---|
| Cooking fat and oil | Goes down warm and liquid, cools and hardens on the pipe wall, narrows the bore over months | Cool it, scrape into the bin, wipe the pan with paper first |
| Wet wipes (all types) | Do not break down; catch on any roughness and build into a mat that traps everything else | Bin. Always, including "flushable" |
| Sanitary products | Designed to absorb and expand — which they do inside the pipe | Bin |
| Coffee grounds | Do not dissolve; settle and compact into a dense sludge, especially in flat runs | Compost or bin |
| Rice and pasta | Keep absorbing water and swelling after they are down there | Bin or compost |
| Cotton buds, dental floss | Rigid or stringy; snag at joints and become the anchor a larger blockage forms around | Bin |
| Nappies | Expand enormously. A frequent cause of complete blockage | Bin |
| Paint, plaster, tile adhesive | Set inside the pipe. Effectively permanent | Dispose of properly — never rinse into a drain |
| Cat litter | Clumping litter does exactly what it is designed to do | Bin |
| Fibrous vegetable waste | Celery strings, onion skins, corn husks tangle and trap | Compost or bin |
This deserves its own section because the labelling is genuinely misleading and it causes an enormous amount of avoidable work.
"Flushable" means the wipe will pass through the toilet. That is essentially the whole claim. It says nothing about what happens over the next thirty metres of pipe.
Toilet paper is engineered to lose structural integrity almost immediately in water. Wet wipes are engineered to do the opposite — they need to stay intact while being used, and that same durability persists in the drain. They arrive at the first joint, root, or rough patch essentially unchanged, and they catch. Then the next one catches on that. Within weeks there is a fibrous mat, and once fat starts binding it together you have something remarkably solid. Water authorities worldwide deal with the large-scale version of this in their pumping stations.
Three things go down a toilet: urine, faeces, toilet paper. Nothing else, regardless of what the packet says. Kitchen towel is not toilet paper either — it is designed for wet strength.
Fat causes more slow-building kitchen blockages than anything else, and it does it invisibly.
You rinse a roasting pan with hot water. The fat is liquid, it goes down easily, nothing appears to be wrong. But a metre or two along, in a pipe surrounded by cool Auckland soil, it cools and deposits on the wall. A film. Then a layer. The bore narrows slightly, which slows flow, which lets more deposit. Repeat over a year and you have a significantly restricted pipe, and eventually something catches.
The give-away is that kitchen drains rarely block suddenly from fat — they get gradually slower over months until something finally tips it over. Once fat has built up, rodding punches a hole through it but leaves the deposit on the wall; hydro-jetting is what actually removes it.
Practically: let fat cool and solidify, scrape it into the bin, and wipe greasy pans with paper towel before washing. It takes ten seconds. In commercial kitchens this is the entire reason grease traps exist — and the reason they need servicing.
Private stormwater drainage is yours to maintain, and it silts up quietly.
None of this prevents blockages caused by tree roots or a failing pipe — those are structural and need investigating. But it removes most of the preventable half.
In practice, no. They pass through the toilet, which is all the label claims, but they do not disintegrate like toilet paper and they catch on any imperfection in the drain. Bin them, including in a modern uPVC system where they simply travel further before causing someone else a problem.
It can soften and move a small amount of recent build-up in the fixture waste. It will not clear an established deposit further along, and boiling water can damage some plastic fittings and seals. It is a mitigation, not a fix.
It is mildly useful for freshening a slow basin waste and it is harmless. It will not clear a real blockage — the fizzing reaction is over in seconds and produces no meaningful mechanical or dissolving action against fat, hair or roots.
We would not. Regular caustic use is hard on older pipework and seals, it does nothing against roots or structural faults, and in a fully blocked line it just sits there, making the job hazardous for whoever opens it. Strainers and a bin work better and cost less.
Enzyme and bacterial products can help maintain a line that is already reasonably clear by digesting organic residue over time. They are a maintenance product, not a blockage clearer, and they do nothing for roots or structural damage.
Lint is the issue — it accumulates like fine fibre and binds with detergent residue. A lint trap on the discharge hose is cheap and effective, particularly in older properties on narrow jointed pipework.
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.