Plumbing question

In reply to TRoglodyte :

Yeah, I just might. We have septic and they aren't a good idea on a septic system anyway.

We have a double sink, so the dishwasher drains above the trap  in one sink and the disposal is on the other sink. Occasionally the water from the 2nd sink won't flow through the disposal properly. Turning on the disposal quickly flushes it. This usually happens when I've dumped a large pot into the sink. It started right after I installed a new disposal, same model, same plumbing. I have no idea why it does it, but I'm sure it would be more frequent if the dishwasher was draining through it, too. I'd drain the dishwasher into the pipe after the disposal and before the trap.

In reply to markwemple :

If you are on septic the sooner the better

I'm on a septic system too.  We don't have a disposal because it's bad for your septic.  Anyway, disposals have a punchout on them to take the waste hose from the dishwasher.  Plumb it up like that and anything the dishwasher pukes out will get ground up to dust sludge in the disposal.

I think the issue here is either a partially clogged drain line (south of the trap) or a clogged vent.

I have a partial clog in my main line that I have to have pro help for.  The snake I have only goes 25'.  I'm fine if I flush the toilet, use the sink, or take a short shower.  But can't do more than one of those within about a half hour of each other.  I know my shower is done when I hear bubbles in the toilet bowl.

I think the other uses are fine, but the dishwasher is just trying to dump very large volumes of water all at once and its dumping water faster than it can make it through the clog.

Edit: This sounds weird to read it, but it does work. 

Fill up the disposal side of the sink and fill the bottom of the dishwasher with water. Turn on the dishwasher so it goes into a drain cycle, plug the other side of the sink, pull the plug on the disposal side, and turn on the disposal. The disposal may pump enough water to push a clog out of the system. I have done that successfully a couple of times at my house. 

Ian F said:

In my minimal experience, it seems a lot of kitchen sinks have a mechanical vent like SVreX mentioned.  My ex's kitchen had one (I replaced it with a fully piped vent) and I suspect mine has one since there is no visible vent pipe in the attic above and a couple of years ago the sink started draining slowly until it just - goes. I think my mother's house has one as well.  Common trait with all three houses is the kitchen isn't all that close to the main stack.

Unfortunately, the vents seems to be invariably buried in the wall behind the sink and replacing it damn near requires a kitchen remodel.  Possibly why some townships have ordinances against their use.  That said, running all of the vent piping was a task and a half in the ex's house, so I can understand why builders would want to use them.

Mechanical vents should never be inside a wall. 

Its not a clogged vent.  If it was, the water would still drain, but it would go glug glug glug.  Vent is above sink.  Water doesn't drain up.  Three things you need to know to be a plumber.  Water flows down hill.  Hot goes on the left.  You get paid on Friday.  Its a slow drain.  Kitchen sink drains, especially ones with the whirling devil attached to them, tend to clog at the very end.  Right where the 1.5 or 2" sink drain ties into either a horizontal 3" or the waste stack itself.  This is because the farther away the solids get, the slower they are moving.  They tend to build up, and up, and up, then bam, you see water in the sink.  The other place they clog is if there is a belly or low spot in the horizontal part of the drain.  Water will sit there.  Any grease or soap will coagulate and float to the top.  Then it sticks to the pipe.  You need to cable the drain.  Put a slight bend in the cable at the very end so it walks itself around the bends as you rotate the cable.  If you can, run the water slowly as you cable.  Put lots of dish soap in the drain as well.  It will help to clean the grease as you cable.  You need to go thru the clog several times to free it.  If its a grease clog and you just go thru it a couple of times, all you are going to do is piss it off even more.  FWIW, I worked for the big rooter company while I was serving my apprenticeship.  Now I'm a real plumber and that place is still as hack as ever.

Sounds like I need a longer snake. I only have a 5 ft. I pulled the trap and ran it a couple of times.

Can get a 1/4" snake to go the full 25' but can only get the 1/2" to go a few feet. Looks like I will have to pop through some drywall in the basement. 

I moved the kitchen in a house once . There was a25' horizontal run in the kitchen pipe. When I cut the pipe it was 7/8 full of grease the whole way across. Sawzall was never the same. 

SVreX

Mechanical vents should never be inside a wall. 

"Should" being the operative word there. As I'm sure you know residential work is often done by those with questionable knowledge of Codes and best practice methods.

As Todd mentions, my ex's house also has a very long horizontal drain from the sink to the main. About 40 feet with barely any pitch at all.  I kept yelling at her when she would pour grease down the drain with the lame excuse, "my mother never had a problem..."  yes dear... and your mother's house has better plumbing. I imagine that drained looked like what Stan described.

In reply to Ian F :

I certainly understand there is a lot of funky stuff in residential plumbing. It has not been my experience to find mechanical vents inside walls routinely. 

SVreX said:

In reply to Ian F :

I certainly understand there is a lot of funky stuff in residential plumbing. It has not been my experience to find mechanical vents inside walls routinely. 

 

It was definitely a "WTF?" moment when we demo'd her kitchen.

The kitchen sink in my house has all sorts of wonky drain work.  I'm not 100% sure it is vented at all, mechanical or otherwise. There's only one vent stack for the house and it's not really close to the kitchen.  It'll be on my list to fix when I get around the renovating the kitchen.  The sink also has an S trap, which is apparently a no-no although how to run the drain any other way is a question I don't have an answer for yet as the drain pipe in the basement is directly below.  I"ll have to do more research for that one.

In reply to Ian F :

Older houses had many vents through the roof. Modern ones only require 1. 

But yeah... wonky is wonky. 

One trick I've used in the past- pour a pot of boiling water down the drain.  If there's grease, the hot water can loosen it up and help it move on through.  Also: garbage disposals are basically an invitation for idiots to play "let's see what I can get to go down the drain!"  We have one in our rental house.  I have found a spoon in it before.  The spoon and the disposal were having an argument.  I lost.  

Fun tale:

Our house has 150 years worth of plumbing in it.

Kitchen sink recently quit draining.  Simultaneously, the downstairs shower quit draining.  The shower was a later addition, so it had a 2" drain pipe, per code.  Kitchen has a 1.5" drain pipe, also per code.

BUT: the motherberkeleyers who put that E36 M3 in plumbed the 2" shower drain tee-d into the 1.5" pipe, which tees into the 4" main sewer pipe (that goes into the septic).  WTF?  You know what that is?  That's like running a 12 gauge wire to a 20 amp plug, and connecting that into a 14 gauge wire that's already serving a 15 amp circuit, and running 14 amp all the way to the main breaker.

Of course, the clog was right where the 2" shower teed into the 1.5" kitchen pipe to the 4" pipe.  I have a 25' hand snake and it finally got the clog out, after disassembling some of the downstairs plumbing.  The clog was (big surprise) a mixture of grease and hair.  (kitchen and shower).  

Added to the list of things to do: separate the kitchen and downstairs shower drain pipes.  

Plumbers (or, perhaps more accurately, people posing as plumbers) can do some crazy-ass things. 

There is definitely a horizontal move below our sink at some point as the basement has a window in the space below the sink. I tried the boiling water trick several times. I also tried a large amount of draino.