When asked “What is a siphon?”, the answer is simple yet vital: A siphon (or trap) is a key component of a residential drainage system that connects your fixtures to the sewage line. Its primary purpose is to drain used water from faucets, filters, or appliances. However, its most critical function is invisible: it protects your home from sewer gases and clogging.
Without a siphon, unpleasant odors, bacteria, and insects from the main sewer line would enter your living space freely.
Here is a breakdown of the different types of siphons and how to choose the right one.
1. Bathtub Siphons
A siphon designed for a bathtub is complex because it manages two water flows: the main drain at the bottom and the overflow protection at the top.
Dual Pipe System: It consists of a drain pipe and an overflow pipe. These two merge into a single outlet that connects to the sewer.
The Overflow: The hole on the wall of your bathtub is not just for decoration; it ensures water doesn’t flood your bathroom if you forget to turn off the tap.
Automatic (Click-Clack) Systems: Modern siphons come with an “automatic waste” feature. Instead of a rubber plug, you simply turn a knob or press a button to close the drain for a bath or open it to empty the water.
2. Washbasin Siphons
Siphons for bathroom sinks come in various shapes and sizes, each with its own pros and cons. The three most common types are:
Tubular Siphon (U or S-Trap): These resemble an English “S” or “U”. They offer excellent water flow and rarely clog. If debris does get stuck in the curve (the “knee”), many models have an opening at the bottom for quick cleaning.
Corrugated (Flexible) Siphon: The most versatile option. It is made of a pleated, flexible tube that can be bent to fit into tight or awkward spaces under the sink.
Pros: Easy to install anywhere.
Cons: The ridges inside the tube can trap hair and grease, requiring more frequent cleaning.
Bottle Siphon (Bottle Trap): The most popular choice for modern bathrooms. Its design is rigid and shaped like a bottle.
The “Jewelry Saver”: This is ideal for families. If a ring or earring falls down the drain, it doesn’t go straight to the sewer. Instead, it settles at the bottom of the “bottle.” You can simply unscrew the bottom cup and retrieve your lost item.
3. Kitchen Siphons
Modern kitchens require heavy-duty drainage.
Branched Siphons: Kitchen siphons often feature multiple branches (inlets). This allows you to connect a dishwasher and a washing machine to the same single drain under the sink.
Double Siphons: If you have a double-bowl sink, branched siphons are essential to drain both bowls simultaneously while managing the discharge from appliances.
4. How Does a Siphon Work?
The operating principle is based on physics, specifically the “Water Seal” (Hydrolock).
Water flows from the sink into the siphon.
It passes through the internal structure (or the “U” bend) and exits into the sewer.
Crucially: A small amount of water always remains inside the curve or the bottle of the siphon. This standing water acts as an airtight plug. It prevents foul smells from rising back up the pipe.
🛍️ Find the Perfect Fit: Browse our collection of Bottle, Tubular, and Designer Siphons here:
Expert Note: If you smell sewer odors after a long vacation, it’s likely because the water in the siphon has evaporated. Simply run the tap for a few seconds to refill the trap, and the smell will vanish instantly.
Conclusion A high-quality siphon is the guarantee of a fresh and hygienic home. You can find all these types—from simple corrugated tubes to sophisticated brass bottle traps—at Merlons.
Frequently Asked Questions (FAQ)
Which siphon is better: Plastic or Chrome (Brass)? – Plastic (Polypropylene) is durable, cheap, and doesn’t corrode, making it great for hidden cabinets. Chrome-plated Brass siphons are more expensive but look much better if the plumbing is exposed (visible) under a wall-hung sink.
Why is my siphon leaking? – Leaks usually occur at the connection points. It is often due to a worn-out rubber gasket (O-ring) or because the nut was screwed on too loosely (or too tightly, cracking the plastic). Check the seals first.
How often should I clean a bottle siphon? – It depends on usage, but generally every 3-6 months. If you notice the water draining slowly, simply unscrew the bottom cup, remove the debris, and screw it back on.
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