Summary
The first possibility for the drain odour, and easiest to remedy, is debris in the drain, itself. This could be a combination of hair, soap, and various hair products that get stuck to the sides of the plastic drain pipes or in the trap underneath the tub. Correctly, you have taken the first step to address this problem with your environmentally friendly drain cleaning method. Unfortunately, while your solution may have temporarily eliminated some of the debris, it may not have cleared the drain of excess hair, which can still allow build-up of new soap and continued odours. While not as green as the vinegar and baking soda mixture, use of commercial drain cleaners may be more effective in removal of excess hair in the drains, allowing proper drainage of soapy water from the tub.
The second location of possible build-up of similar materials may be more insidious. All bathtubs have an overflow drain near the top of the tub that is rarely needed, unless the tub is overfilled. It is common for some people to fill the tub with too much water, so that a significant amount is drained through the overflow, once they enter the tub and displace some water. If this water is full of soap, bath oil, or bubble bath, it may also be causing a build-up within the overflow waste piping. This piping is connected to the drain piping below the tub, so an odour could easily be detected through the drain at the bottom of the tub, if this were the situation. The same "sniff test" you did on the tub drain should be done at the opening in the cover to the overflow, which is located below the tub spout. If the smell is stronger in this area than at the drain, the cover should be carefully removed and drain cleaner or a pipe cleaner used to clear this area, as well.See the full content of this document
Extract
Many Causes for Plumbing Odour
Ari Marantz --Ask the expert
Q: We purchased a five-year-old, three bathroom, cab-over home two years ago and noticed an unpleasant odour in one of the bathrooms. This odour appears to be worse in winter. We checked the floor for mildew, etc., when we had the bathroom floor tiled this wi...See the full content of this document
If you are already a vLex customer, access here