Sewage smell after a holiday: what does its return tell you?

Why absence is relevant information

A classic siphon holds a quantity of water between the room and the drain. That water barrier stops sewer gases. Buildwise explains that little use by evaporation can reduce the water lock. Therefore absence is relevant context, without any odour problem being explained after holiday.

Note which sanitary fixtures are little used: for example the shower in a guest room opposite the daily washbasin. You don't have to loosen the siphon to give this overview. Also tell me if you noticed the smell earlier and what was then investigated or modified.

Sources: Buildwise Magazine July–August 2024 — traps and water seals, p. 12–13

Note the gradient, not only on the first impression

Describe what you notice during normal use. Does the nuisance disappear and stay away, or is the smell present again the next morning? Does it occur with the use of another device? A short timeline gives the performer targeted questions without conducting a pressure test or recovery attempt.

Buildwise also mentions pressure fluctuations in the drain: they can disrupt the water lock. That's something other than pressure on the drinking water line. A complaint that returns after use may therefore require an assessment of the drainage and ventilation. Adding extra water yourself is not automatically a lasting solution.

Sources: Buildwise Magazine July–August 2024 — traps and water seals, p. 12–13

Sanitary drainage and ventilation can touch each other

Do you smell it especially at an air supply opening, then literally mention it. Zehnder describes that sewer air can also be sucked from the outside with a heat recovery system. Such a route requires a different assessment than only the drain under a sink.

So do not just replace an entire ventilation unit or any siphon adders based on the smell. Make a simple plan with the spaces involved and the place where you notice the inconvenience. Photos of the accessible surroundings are sufficient; roofs, shafts and concealed connections are left for appropriate professional assessment.

Sources: Zehnder possible routes of sewer air at heat recovery

Do not make a risky test of an unknown smell

Smell gas? Go outside and call 0800 65 0 65. Follow the separate safety instructions for gas smells and CO. Appointing an unknown fragrance as a "smell" is not a reliable exclusion from danger; use this article only for a non-acute discharge complaint.

Do not pour any mixture of plungers or cleaning agents into a drain and do not place yourself a new component to seal the odour. When applying, please indicate which products or interventions have already been used. That's relevant security information, not a reason to conceal an earlier attempt.

Sources: Fluvius — safety instructions if you smell gas

Prepare a defined sanitary demand

Please indicate your address, the period of absence, affected devices and progress since homecoming. Also note slow running water or drinking sounds when you notice them during normal use. Let the performer determine which combination of tests is required; the observations are not remote diagnosis.

Wattra looks at sanitary questions throughout Flanders and discusses what is possible within the assignment. At an apartment you also report the situation to the responsible administrator when common areas may be involved. Specialist drain unblocking, leak detection or work on the public sewer system is not automatically included.