Vesilukko

Vesilukko, also known as a trap or S-trap in English, is a plumbing fixture designed to prevent sewer gases from entering a building. It is typically located beneath sinks, toilets, and other plumbing fixtures. The vesilukko works by retaining a small amount of water in a U-shaped section of pipe. This water creates a seal that blocks the passage of unpleasant odors and harmful gases from the sewer system.

When water flows through the fixture, it fills the U-bend and then drains away, leaving behind a small residual amount of water. This retained water is crucial for the functioning of the vesilukko. If the water seal were to evaporate, due to prolonged disuse of a fixture, for instance, sewer gases could then escape into the living space. This is why it is recommended to periodically run water in seldom-used drains.

The design of the vesilukko is simple but highly effective. Variations exist, such as P-traps, which are more commonly found in newer plumbing systems and are designed to prevent gases from entering from a horizontal pipe. Despite these variations, the fundamental principle of using a water seal to block gases remains the same. Regular cleaning of vesilukot is important to prevent blockages and ensure proper drainage and gas sealing.