Backslope and drainage in a sewer line! Professional opinions.......

[ff347]

Well after living in the same house since 1998 we had the first sewer line backup, thankfully not a bad one (if that is possible). I have one spot that has a little sag in the main line, water is sitting in that spot. We confirmed this with a camera and other than that one spot he says it all looks good.

Got a question for the plumbers out there, is it possible to cut about two inches out of the vertical lines(black plastic pipes), connect them with fernco's and create a little more slope. The plumber said it could/should take care of the problem and would be an "easy" fix. I know that a little slope or to much is bad, I have one spot in the main drain line that caused the problem. I can give dimensions, specs and hell I will take pictures for greater detail if anyone has an educated opinion if this is actually a good idea or not. He offered two repair prices, one for basically what I described and one for replacing everything. I think the pricing is ok it is more along the lines of the A/C is on the way out too and money is a tad tight.

 

[KLF]

Ya pictures would help.

Minimum slope on sewer lines is usually about 0.0050 (0.5%, or ~3/4" drop per 10' length), but that is risky. You want enough slope to keep small solids from settling. Minimum slope on septic systems here on this pipe is 2%, which is 1/4" per foot.

 

[ff347]

Pictures in the next day or so. Thanks for the help. This is not a septic system.


Oh, the problem is under the house in a crawlspace. I am thinking that the age of the pipe(house was built in 83) and maybe not enough support has slowly caused the pipe to sag? I will get under there with a level and check the slope when I take the pictures.

 

[jynx]

We generally try to get 1% (0.01 ft/ft) when going from a house to the main. Not sure too much fall is possible, I mean I wouldn't want 20% or anything, but I have have mains upwards of 7% on some projects.

As far as the fernco, yes you could cut the pipe and piece it back together. I am personally not a fan. Using a glue joint union would be my preference and make sure you support it because a fernco could pull apart if the lower pipe is just hanging in it.

Best advice I can give, don't pour grease down the sink. You may not, but if you do that is a super no-no. I'd say 90% of problems will trace back to grease + something else in the lines.

 

[ff347]

Thanks for the help. Spent some quality time under the house with my trusty sawzall and took out 3.5" and put a level on every piece of that pipe. All good now, went with just a little over 1/4" a foot.