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A blocked drain is rarely a mystery — it's a short list of usual suspects and a method for ruling them out, one at a time.
Short answer first: try hot (not boiling) water with washing-up liquid down the plug, then a plunger with a wet cloth over the overflow. Skip harsh chemical cleaners on older pipework. If it comes straight back, or more than one drain in the house is affected at once, ring 020 4577 2888 any hour rather than keep guessing.
Hot water and washing-up liquid first, then a plunger. Skip the caustic bottle unless you're sure the pipework can take it.
Start gentle. A kettle of hot — not boiling, which can crack older plastic traps — water mixed with a squirt of washing-up liquid, poured slowly down the plughole, cuts through a good deal of the grease and soap scum that narrows a pipe over weeks. Give it ten minutes to work before running the tap.
If that doesn't shift it, a plunger is next: block the overflow with a wet cloth first so the plunger's force goes down the pipe instead of hissing out the overflow hole, then work it in firm, steady strokes rather than one big shove. For a bath or sink this clears the majority of everyday blockages. A set of flexible drain rods, sold in most hardware shops in town, will reach further into an external gully than a plunger ever will, and are worth keeping if your house has a history of slow drains.
Examiner's note: gentle methods first, in order. Reaching for the strongest chemical on the shelf is a shortcut that often costs marks later.
Fat, oil and grease top the list — followed by wet wipes, cotton buds and anything that doesn't dissolve. None of it belongs in a pipe, ever.
Fat, oil and grease are the single biggest cause of household drain blockages, and the mechanism is simple: they go down warm and liquid, then cool and set hard against the pipe wall further along, narrowing it a little more with every pour. Let cooking fat cool in a container and put it in the bin instead — it costs nothing and prevents almost everything.
The second offender is anything marketed as "flushable" that isn't, in practice: wet wipes, cotton buds, dental floss, sanitary products. They don't break down the way toilet paper does, and they're the most common cause of a blocked toilet or a snagged sewer pipe. A small bin beside the toilet solves this permanently, and it's the cheapest piece of plumbing advice on this whole site.
Examiner's note: "it went down fine" is not evidence it was safe to flush — it just means the blockage is forming somewhere you can't see it yet.
Clear visible leaves and silt from the grate yourself — that's safe and often enough. If it refills within minutes of rain starting, the blockage runs deeper.
Outside gullies collect leaves, grit and general garden debris, and in autumn especially they can silt up enough that heavy rain simply has nowhere to go. Lifting the grate and clearing what you can see and reach is safe, sensible, and something most households can do without a second thought.
If the gully empties fine between downpours but backs up again the moment rain starts, the obstruction is further down the pipe run rather than in the trap itself — sometimes tree roots finding their way into an older clay pipe, common in some of Magherafelt's longer-established streets, or a collapsed section further along. That's a job for drain rods or a camera survey, not a garden trowel.
Examiner's note: a gully that floods every single time it rains, at the same spot, is describing its own fault location. Listen to the pattern.
One house affected: probably your own drain. Several neighbouring properties affected at once: probably the shared public sewer. NI Water is the public sewer authority in Northern Ireland.
The general split works like this: the pipework serving your property alone, up to where it joins the shared system, is generally the owner's responsibility to maintain and clear. The public sewer that several properties drain into — and the pumping stations and larger pipes beyond it — is NI Water's to look after. A single blocked sink or toilet in your own house is almost always your side of that line.
The signal that flips the picture is scale: if your neighbours are reporting the same overflowing gully or backed-up toilet at the same time as you, especially after heavy rain, that's a strong hint the blockage sits in the shared sewer rather than in any one house's private pipework, and it's worth reporting to NI Water rather than paying privately to have your own drain rodded when the fault isn't actually there.
Examiner's note: "everyone on the street has it too" is the single most useful sentence you can open a call with. It changes who should be doing the fixing.
Possibly — a tank that's due to be emptied, or a failing soakaway, can mimic a blocked drain across the whole house. Worth ruling out before assuming a pipe fault.
Septic tanks are common across the rural townlands around Magherafelt, wherever mains sewerage doesn't reach — out toward Desertmartin, Knockloughrim and the smaller settlements between the town and the Sperrin foothills. The tank needs periodic emptying by a licensed contractor, and when it's overdue, or the soakaway that disperses treated water has become waterlogged or blocked, every drain in the house can slow down at once in a way that looks exactly like a single blocked pipe.
The tell is again the pattern: a genuine pipe blockage usually affects one fixture first — one slow sink, one gurgling toilet. A tank or soakaway problem tends to affect everything roughly together, and often comes with a smell outside near the tank itself. Note when the tank was last emptied when you call; it's one of the first questions worth answering.
Examiner's note: "every drain in the house is slow" and "one sink is blocked" are different questions with different answers. Don't answer the wrong one.
Sparingly, and never on a drain that's completely blocked with standing water sitting in it — the chemical just sits on top doing nothing useful while soaking your pipework. They're also a poor match for older cast iron or lead-era pipework, common in Magherafelt's town-centre terraces, where repeated caustic use can accelerate corrosion. A plunger, hot water and washing-up liquid, or a drain rod solve most household blockages without the risk.
A partial blockage is usually grease, soap scum or hair narrowing the pipe rather than sealing it shut completely, and it nearly always gets worse rather than better on its own. Treat a slow drain as an early warning: try the hot water and washing-up liquid method now, while it's still a five-minute job, rather than waiting for it to seal completely at a less convenient hour.
Usually yes — leaves, silt or grit build up in the gully trap or the pipe running away from it, and heavy rain then has nowhere to go but over the top. Clearing visible debris from the grate yourself is safe and often enough; if it refills within minutes of rain starting, the blockage is further down the run and worth a proper look.
It's worth ruling out before assuming a pipe blockage, especially if every drain in the house is slow at once rather than just one sink. Septic tanks need periodic emptying, and a tank that's due, or a soakaway that's failed, can back the whole system up in a way that looks exactly like a blocked drain but has a different fix entirely. Say when it was last emptied when you call.
It depends entirely on your own policy — some buildings policies cover drain clearance and resulting damage, others exclude gradual blockages as wear and tear, and septic tank systems are often treated differently again. Check your policy wording or ask your insurer directly rather than assuming either way, and keep any invoice in case a claim becomes relevant later.
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