Siphon Replacement in Warsaw — When to Replace and How It Works

The siphon — or trap — is the curved fitting under your sink, bathtub or shower that holds a plug of water to block sewer gases from entering the room. As long as it works, nobody gives it a thought. Trouble starts when the plastic cracks with age, rubber seals dry out, or a blockage refuses to clear no matter what you pour down the drain. Then a puddle appears under the basin and the bathroom starts smelling like a sewer. In older buildings around Srodmiescie and Wola we regularly find traps that have been in place for 15–20 years — they crumble the moment you try to unscrew them.

Safety note: waste-pipe work demands care. A poorly assembled trap means a leak that can ruin the vanity unit beneath or seep through to the flat below. If you are unsure about pipe diameters or connection types — call a professional.

How much does siphon replacement cost

The price depends on the trap type (bottle trap, tubular trap, flat shower trap, bath trap with overflow) and how accessible the connections are. If the pipes are in good shape, the swap takes half an hour. If the old trap is seized or the waste pipe needs an adapter — it takes longer and costs more. Fixings are included in the price; the trap itself is supplied by the client (or we can source and bring one for an additional fee). Current rates for all bathroom services are in the table below.

How the replacement works

1. We shut off the water and place a bucket or basin under the trap — there is always water sitting inside it.
2. We unscrew the old trap: disconnect it from the basin waste outlet (or bath waste) and from the drain pipe. If the plastic is brittle, we work carefully to avoid snapping the spigot in the wall.
3. We clean the waste outlet thread and the edge of the drain pipe, removing old sealant, limescale and grime. This matters — new seals must sit on a clean surface.
4. We assemble the new trap: fit the waste outlet with a fresh gasket, attach the trap body, connect the outlet to the drain pipe. All nuts are hand-tightened only — plastic threads crack under a wrench.
5. We turn the water back on, fill the basin and release it. Every joint is checked with a dry paper towel wiped along the seams. If anything is damp — we snug the nut or swap the seal.

Common mistakes

• Using a wrench on plastic nuts — the thread splits and the trap leaks immediately or within a week.
• Buying the wrong diameter — the standard for a basin is 32 mm, for a bath 40 mm, but exceptions exist. Measure before you buy.
• Fitting a new trap with old rubber seals — the rubber is already deformed and cannot seal properly.
• Not cleaning the drain pipe of old sealant — the new compression ring seats unevenly and drips.
• Ignoring alignment: if the basin waste and the drain inlet are not on the same axis, the trap sits at an angle and will eventually leak.
• Boxing in the trap after a renovation with no access panel — traps need periodic cleaning and must remain reachable.

What to prepare before the visit

• Clear the space under the basin (or access to the bath) — remove cleaning products and anything in the way.
• If you have already bought a new trap — check that the diameter matches your basin and drain pipe.
• Have a cloth and a container ready — water will spill when the old trap comes off.
• Know where the isolation valve for your flat is located.
• If the problem is with a bath or shower — make sure the inspection hatch is accessible (if one exists).
• If the building has old cast-iron drainage — let us know in advance, an adapter may be needed.

A real case from Warsaw

We were called to an older flat in Srodmiescie — a permanent puddle under the bathroom basin. The owner had tried to tighten the trap herself, but the plastic was so old that the nut cracked in her hands. The trap had been there for about fifteen years, yellowed and brittle. The drain pipe was cast iron with a rough edge. We removed the remains of the old trap, cleaned up the cast-iron pipe edge, and fitted a rubber reducer from 50 to 40 mm. The new bottle trap was connected in twenty minutes. We tested — completely dry. The whole job took about forty minutes including cleaning the old pipe.

Frequently asked questions

How long does a siphon replacement take?
Between 30 minutes and an hour. If the pipes are in good condition and diameters match — faster. If an adapter or cast-iron cleanup is needed — longer.

Can I replace the trap myself?
For a simple basin — yes, if you have the right diameter and type. But if the connection is non-standard, the pipe is cast iron, or it is a bath trap with overflow — better to call a professional to avoid a leak.

How often should traps be replaced?
Plastic traps last 10–15 years. If you see cracks, yellowing, or a persistent smell despite a functioning water seal — it is time for a new one.

What if it smells like sewage but the trap looks fine?
Check whether the water seal has dried out (this happens when a basin is unused for a long time). Run some water and wait. If the smell persists — the issue may be with the stack vent.

Does the same trap fit a basin and a bath?
No. A basin waste is 32 mm, a bath waste is 40 mm, and the bath also has an overflow. They are different products.

What about a kitchen trap?
Same principle, but kitchen traps often have a double bowl, a dishwasher branch or a disposal unit connection. We replace kitchen traps as well.

Book a siphon replacement

A leaking or blocked trap is a small thing that quickly turns into a real problem: a soggy cabinet, a bad smell, a damaged floor. The replacement takes under an hour and the result is dry, odour-free plumbing for years. We work across Warsaw and arrive with tools and standard consumables. Get in touch — we will sort it out at a time that suits you.