Smells, slow flushing or overflowing WCs, effluent or dips in the ground near the inspection chambers, septic tank, cesspit or treatment plant
Arogleuon, toiledau sy'n fflysio'n araf neu'n gorlenwi, elifion neu bantiau ar y llawr ger y siambrau archwilio, y tanc carthion, y carthbwll neu'r ganolfan drin