A blocked drain always seems to happen at the worst possible time. Guests are over, dinner is cooking, and everyone needing the shower. The good news is that most blockages aren’t random. They’re caused by the same few things over and over. Here are the main culprits that slow, stink, or choke drains in Christchurch homes… and what to do about them before you need an emergency callout.
1. Grease and fat
Pouring oil, fat or cooking grease down the kitchen sink might feel harmless because it goes down as liquid. The problem is, it doesn’t stay liquid. As it cools inside the pipe, it hardens and sticks to the walls. Layer after layer builds up until your sink starts draining slower and you’re standing in dirty dish water wondering why nothing’s moving.
Tip: Let fat cool in a container, then bin it. Wipe oily pans with a paper towel before washing. It takes a few extra seconds and can save you from needing a hydro jet through your kitchen line.
Signs this is your problem: slow kitchen sink, gurgling sounds, bad smell coming from the plughole.
2. Hair and soap scum
Bathroom drains are repeat offenders. Hair, soap residue, and body products all collect under the shower or basin trap and form a thick, sticky mass that water can barely move through. Over time, that turns into a near-solid blockage.
Tip: A simple hair catcher over the shower drain can make a huge difference. It’s not glamorous, but neither is ankle-deep shower water.
Signs this is your problem: shower or vanity draining slowly, standing water around your feet, that “wet dog” smell in the bathroom even when it looks clean.
3. Foreign objects
Drains are only designed for water, toilet paper, and… you know. Anything else can cause trouble fast. Common issues include: wet wipes (even the ones that say “flushable”), cotton buds, sanitary items, kids’ toys, paper towels, nappies, dental floss, even too much kitchen roll used as toilet paper when the loo paper ran out.
Tip: If it’s not standard toilet paper, don’t flush it. Bin it. Especially wipes. Wipes cause absolute chaos in sewer lines.
Signs this is your problem: toilet water rising instead of dropping when you flush, toilet almost overflowing, or bubbling in the toilet when another fixture drains (like the basin or shower).
4. Tree roots
This one is a big Christchurch classic. Tree roots love moisture. If there’s even a hairline crack in an older earthenware or PVC pipe underground, roots will find it, get inside, and grow. Over time they fill the pipe, slow flow, catch other debris, and eventually choke the line completely. Heavy rain will then push everything back towards your house instead of away from it.
Tip: If you’ve got repeat blockages outside, especially after rain, or a gully trap that overflows out in the garden, it’s time to get a CCTV drain camera inspection. You won’t “plunge” tree roots out of a pipe. You need proper cutting/jetting gear and often a repair.
Signs this is your problem: gurgling sounds, smells outside, stormwater backing up, repeated blockages in the same line every few months.
5. Cracked, sunken, or blocked pipes
Sometimes the pipe itself is the problem. Older drains can crack, collapse, or sink over time, especially in areas affected by past ground movement. When that happens, water can’t run through smoothly. It sits, it collects solids, and before long, you’re dealing with a full blockage and that lovely “what is that smell?” moment.
Hard water can also leave behind mineral deposits inside the line. Over years, that build-up narrows the pipe and makes even normal use feel like overload. Think of it like cholesterol in an artery.
Tip: If you’re getting constant repeat problems even after clearing a blockage, don’t just keep paying for emergency unblock after emergency unblock. Get it properly inspected, mapped, and repaired. It costs less long-term than living with a pipe that’s dying under your lawn.
Signs this is your problem: constant “mystery” blockages, smells coming back even after you’ve cleared the line, slow drains in multiple areas of the house.
How to know when it’s time to call a professional
- The toilet’s about to overflow and you’re panicking
- You’ve tried a plunger and nothing changed
- You’re getting that sewer smell inside or outside
- The same drain keeps blocking again and again
- There’s stormwater coming up where it definitely shouldn’t
At that point, it’s not just an inconvenience. It’s a health problem, a flooring problem, sometimes even an insurance problem if it floods.
That’s where proper gear matters. A blocked drain isn’t always “just hair” or “just fat”. It can be roots, broken pipe, sunken pipe, or a full collapse. We use high-pressure hydro jetting to clear the line, and CCTV drain cameras to see what’s actually going on so the fix is real, not temporary.
Need it sorted?
If you’re dealing with a blocked toilet, a slow sink, a shower that won’t drain, or stormwater backing up, call Drainage King on (03) 365 4642. 24/7 emergency drain unblocking across Christchurch, Selwyn, and Waimakariri.
Get it cleared properly. Get the flow back. Call the King.