Readers help sniff out septic-system smell
We're fulfilling that promise and making another: This is it for anti-stink stories. (At least for a while.)
Q: I had the same problem when we moved into our house. We live on the top of a ridge and have a slope with tall trees at the bottom. The wind hits the trees and goes over them into the less-treed slope in the back yard before hitting the house side and the roof. As your inquirer noted, they smell it on days when there is little or no wind — the same as I did. I determined that even very light winds were able to make the vent pipe create a venturi effect and suck the sewer gas out of the pipe, over the roof and deposit it in the front yard. I was able to confirm this using a lighted incense stick.
First I tried one-way vents. Spiders fouled them up after a year. Then I thought about how a venturi works: Wind goes over pipe, creating a negative pressure and sucks out gas. I purchased "P" traps and placed the "U" bend on the top of the vent stacks. The upside-down "U" opening was placed on the downwind side of the vent pipe, preventing the wind and the pipe from creating a venturi. Problem solved for the last 13 years.
A: Now there's a use for incense I had never considered. Remembering back to college days, though, I personally would be hesitant with a lighted match around all that sewer gas.
Q: The (so-and-so) Plumbing franchise has a (blank) product called "(nope, not telling)." This product will not only eliminate the smell, it also will eliminate the need to pump the septic tank. It is an approved, environmentally safe, biodegradable live bacteria that actually "eats" the solids in the tank. This treatment is also great for all the drains in the house.
A: Nice try at a free product plug, but county and state departments of health specifically recommend against these products in septic systems, and have for years. However, due to their popularity, and the drainfield and groundwater damage caused by their use, in 1994 the State Department of Public Health was required by the Legislature to "approve" any product for use in the state that does not cause harm to a septic system or groundwater. This approval clearly does not constitute an endorsement of any product claims. (For a list of approved products, see www.doh.wa.gov/ehp/ts/pubs.htm#Wastewater.)
Appropriately, when a product is approved under RCW 70.18, a manufacturer must not claim that the product reduces the frequency or need for pumping. The state attorney general and/or local prosecuting attorneys are given direction in law for prosecuting such individuals/companies.
In other words, these widespread claims are totally bogus and illegal. Knock it off, and don't make me slap you guys again.
Q: One application packet of dry yeast flushed down a toilet improves it almost immediately.
Q: Many installers haven't caught on to proper maintenance procedures. They will open the lid and say it's working fine. If lab tests haven't been performed, the installer cannot say whether the system is really working properly. A proper test will measure critical levels of system performance including biochemical oxygen demand (BOD); presence of fats, oils and greases; and other factors. A good maintenance company also will educate the owner on proper system usage, which is excellent insurance against another system failure. For example, chlorine tablets in toilet tanks will kill beneficial bacteria in the septic tank.
Maybe the owners know how to use a private septic system, and weather conditions at the site just don't carry the vent fumes away properly. Vents are at the top of the house for a reason. If this is the case, an activated charcoal filter can be installed on the top of the vent pipe. The activated charcoal should be a type specifically made for odor control. This WILL eliminate the odor. There are some liquid products containing enzymes and bacteria claiming to reduce odors by treating the septic tank. What these products do is make up for an owner's improper usage. A properly used septic system should not need any additives.
Q: Possible that he has one or more plugged vents that cause the odors to be concentrated in one area, so I suggest that he inspect the vents. Insects could have blocked them. I had a new roof put on a few years ago, and the roofers put lead covers over the vents and folded the soft lead down into the opening. This restricted the venting. Fortunately, it was easy to fix.
Q: I solved a similar problem by extending the vent pipes a couple of feet. Probably only one vent is responsible, depending on the wind, and the aerodynamics of the roof. The hard part is connecting it so as to keep rain from going down the outside of the pipe into the attic. I used bathtub caulk. Lots of it.
A: Bathtub caulk! They make permanent gaskets for this, friend.
Q: My dad had an identical problem after he built a garage close to his house. He solved it by extending the roof vents.
Q: I cut a few 3-foot lengths of black PVC piping and slipped them over the vents, thus raising the level a few inches. This was enough that the odor cleared the roof instead of wafting down into the yard. I never had the problem again. Years later I removed the PVC and by then the tank had apparently stabilized, and the problem never returned.
A: You are among the many vent-extenders who wrote in with essentially the same experience and outcome.
Darrell Hay answers readers' questions. Call 206-464-8514 to record your question, or e-mail dhay@seattletimes.com. Sorry, no personal replies. More columns at www.seattletimes.com/columnists.