How to Unclog a Drain (And When to Stop Trying)

It's half seven in the evening, the sink is full of grey water that isn't going anywhere, and every search result is telling you to pour baking soda down it. Here's the thing most of those guides won't say: some fixes are worth your time, some do nothing at all, and a couple will genuinely make the job worse. As Dublin plumbers, we spend a fair chunk of our week finishing what a bottle of drain cleaner started.

So this is the order we'd actually try things in at home, quickest and safest first, and just as importantly, the point where you should put the tools down and ring someone.

First, a quick triage question

Before touching anything, check whether it's just one fixture or several. If only the kitchen sink is slow, the blockage is almost certainly close by and you've a decent chance of shifting it yourself. 

If the sink, the shower and the toilet are all sluggish, or there's water sitting in the gully outside, the problem is further down the run and nothing you pour into the sink will reach it. That second scenario is a stop sign, and we'll come back to it.

Fix 1: hot water and washing-up liquid (five minutes)

For a slow kitchen sink, this is the one to try first, because most kitchen blockages are congealed fat and grease. Squirt a generous amount of washing-up liquid down the plughole, follow it with a full kettle of hot water poured slowly in stages, and give it a few minutes between pours.

The detergent breaks the grease down and the hot water carries it off. One caution: if your sink is acrylic or a composite like granite, use hot tap water rather than a boiling kettle, since the heat can damage the material.

Fix 2: the plunger, done properly (ten minutes)

Most people plunge badly and give up. The trick is the seal: block the overflow hole with a wet cloth, and if you have a double sink, hold a second cloth firmly over the other plughole, otherwise you're just pushing air around the system.

With a few centimetres of water in the sink, place the plunger over the drain and work it up and down briskly for thirty seconds or so. It's the repeated pressure change that breaks the clog loose.

Fix 3: open the U-bend (twenty minutes, one bucket)

This is the step most DIY guides skip, which is odd, because the majority of sink blockages live in the trap directly under the plughole and you can reach them with your hands. Put a bucket underneath, unscrew the two connectors on the U-shaped section, and let it drain.

Whatever's in there, and it's usually a greasy plug of food scraps or a slimy knot of hair, comes out with the trap. Rinse it in a different sink, screw it back hand-tight, and run water to check the seals.

Important: only do this if you haven't poured chemical drain cleaner down first. Opening a trap full of caustic liquid is how people end up with burns, and it's the main reason we'd rather you skipped the chemicals entirely.

Showers: it's hair, deal with the hair

A slow shower drain is a hair problem until proven otherwise. Lift the cover off the plughole, pull out what you can see (rubber gloves recommended, it will be grim), then use a cheap plastic drain stick or a bent wire hook to fish out the mat of hair sitting just below.

Follow with hot water and detergent to clear the soap scum binding it together. Doing this every couple of months keeps the shower draining properly and costs nothing but two unpleasant minutes.

What about baking soda and vinegar?

The internet's favourite fix, and honestly, it's mostly theatre. The fizzing is a simple acid-base reaction that produces carbon dioxide and water, and the chemistry behind the fizz is real enough, but the two ingredients largely neutralise each other rather than dissolving a compacted plug of grease and hair.

It'll freshen a smelly drain and might help a very mild build-up. On a genuinely blocked drain, in our experience it does next to nothing except delay the fix that works.

The one we'd skip: caustic drain chemicals

Strong chemical cleaners promise the world and cause a surprising share of our call-outs. They rarely clear a solid blockage, they can damage older metal pipework and the rubber seals in your trap, and if they don't work, they leave a sink full of caustic water that someone (often us) has to deal with by hand.

If two rounds of plunging and a clean trap haven't fixed it, chemicals aren't the missing step. The blockage is somewhere you can't reach.

If more than one fixture is draining slowly, the blockage isn't in your sink. It's in the pipe run, and nothing you pour down the plughole will reach it. 

Sean Abbington, Director of Abbington Property Maintenance

When to stop trying

Here's the honest line between a DIY job and a plumber's job. Stop and call someone if:

• More than one fixture is slow or backing up at the same time

• Water is rising in the gully or a drain outside

• Anything is coming back up, especially into the bath or shower, which sit lowest in the system

• There's a persistent bad smell even when things seem to drain

• The same drain keeps blocking every few weeks, whatever you do

Pushing on past this point usually means forcing the blockage further along the pipe and compacting it, which turns a straightforward rodding job into something longer and dearer.

A recurring blockage in particular is worth investigating properly, because in older Dublin houses it often traces back to cracked clay pipework or tree roots rather than anything you did wrong at the sink. 

In Dublin and your Drain Still Clogged? Give Us a Call

Try hot water and detergent, plunge properly, open the trap if you're comfortable, and pull the hair out of the shower. That sequence clears most everyday blockages in under half an hour without a cent spent on chemicals. 

When the signs point past the trap, that's exactly the job our drain team handles every day across Dublin, with rodding, jetting and CCTV surveys for the stubborn ones, and we answer 24/7. 

Blocked drain that's beaten the plunger? Call Abbington on 087 465 8338 and we'll sort it, day or night.