titanax 0 Report post Posted August 18, 2010 (edited) So my understanding of P-trap is that since the P-trap is vented the water that it holds to prevent sewer gasses from coming back in will not be siphoned out. The S-trap however is not vented therefore vaccum can build up allowing the water to be siphoned and sewer gasses to enter. Apparently S-traps are no longer legal in the U.S & Canada. However it does not appear to be a problem here in SG, so the question still stands, why choose 1 over the other? Is it because our waste management is much more advanced & so the trap designs do not matter? How about choking issues? Any expert advisors? Edited August 18, 2010 by titanax Share this post Link to post Share on other sites
