By Russ and Tiña De Maris
If your RV is connected to a sewer drain most of the time, you probably keep your gray water valve open. This can lead to a smelly little problem: Sewer gases arise from the sewer hose into your gray tank, and slowly migrate up the through the tank and out the roof vent. At times those same evil essences can somehow reinfiltrate your RV with a negative impact on your olfactory organs.
Worse still, if there are any “vague” connections in your gray water venting system, those nasty little essences can also make their creepy way out, carrying not just the odor of gray water (as bad as that is!) but with a direct connection to the city sewer (or local septic system), that really horrific scent of black water can invade your premises.
What to do? Enter the Folgers P-trap solution. If you leave your sewer hose connected and the dump valve open, stick a P-trap between the sewer and you. Simply obtain a coffee can (or a large rock) and make a bend in your sewer hose, as illustrated in the photo here. Gray water will advance over the bend, but the water trapped in the hose on the “rig side” of the coffee can will prevent the odoriferous fumes from crossing over.
Mind you, when you dump your black water you’ll want to temporarily remove the coffee can to allow a free-flow of black water, et al, to make the trip down the sewer unimpeded. One more thing: If your travels take you to the cold country, don’t use this lash-up in below-freezing weather — you’ll get more than just stink back!