Common in Tsuen Wan
older estates share stack vents; newer Belair-zone blocks isolated.
Try these 3 before calling
1. Pour 1L water down floor drain — fixes dry P-trap (~30% of cases) in 60 seconds.
2. Clear hair from sink + shower drains — biofilm removal starts here.
3. Cling-film test — cover each drain overnight to identify the source. Full guide.
What we do on a Tsuen Wan call
4-source diagnostic first
Smoke + ammonia test locates the source in 15 min. Targeted treatment (enzyme for biofilm, gasket replacement for broken seals, water-fill for dry trap, overflow flush for sink). 30-min retest. WhatsApp before/after photos.
Tsuen Wan pricing
Starting HKD 800 for in-flat bathroom drain odour diagnostic + treatment in Tsuen Wan (residential). Includes 2-hour typical response, 4-source diagnostic, targeted treatment, 30-min retest, WhatsApp photos.
40-55 min NT typical window. NT +HKD 50. Out-of-hours +HKD 200.
Parts at cost: P-trap gasket HKD 30-80, full P-trap HKD 150-500 if cracked. Stack-level work requires OC sign-off, typically HKD 1,500-3,500.