# Is my bathroom too far from the septic tank



## HTG_zoo (Apr 18, 2011)

I live in a very long modular home with 2.5 bath. The half bath and the main bath are close to the septic tank, just a straight drop and 20-30 foot run to the tank for those. The kitchen is set a little further from the tank and makes 2 turns and about a 60 foot run to the tank. The master bathroom is even further away. Waste water from the master bath makes a 10 foot run to the center of the house then runs the length of the house to to tank, about 110 feet total. The drains drain slow back there, the toilet barely flushes and the shower back there isn't even plumbed in to the drain!

We haven't used the master bath and haven't bothered to correct whatever ails it. I think it's too many 90 degree angles and a spot where waste water needs to flow uphill because the pipes are poorly arranged. Now I need to fix this up so we can remodel the main bathroom. My father and I have done lots of plumbing projects (installed several bathrooms over the years) but never anything so far from the main sewage drain line.

He thinks that if I correct the over use of 90 degree angles, install wider drain pipes and correct the pitch of the drain lines that the back bathroom will be fine. He's never been under the house. I can get 5 degrees slope from the master bath pipes to the septic line under the center of the house, but I can't get any slope on that line. The main line to the septic tank exits the foundation level with the main septic line all the drains tie into.

I'm wondering if I need to set up a pumping station some where between where the kitchen and master bath tie in.


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## Curtis B (Aug 15, 2008)

You only need 1/4" per 3', so you would need a 28" drop over the 110' of the line. I would run a central line, and tie each line/fixture in individually, unless some are inline, then tie those together, then to the main line. I can't imagine having to install a sump, but if you can't get the slope, you might have to.


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## Harry Chickpea (Dec 19, 2008)

As far as sewer lines go, that is a short one. Commercial buildings have sewers that run hundreds of feet without pumps or assistance. It may seem counter-intuitive, but _you can't run sewer lines at a steep angle and expect them to work_. They really do need to run almost flat, so that the liquids don't leave the solids stuck to the walls of the pipe. Curtis is spot on in the percentage of pitch he gives.

A larger diameter pipe may actually work against you. 3" is fine. Any tendency to clog has more waste water acting directly on the clog material.

You say that the shower is not even plumbed in. If anything, non-use of the shower might be contributing to your problem. Modern toilets are low water usage, which means there isn't sufficient water flow to flush the solids forcefully down the entire length of the run. Taking a shower would supply the water needed to flush the line periodically.

If you have a low spot in the sewer line, that needs to be corrected. If you have a nearby utility room where you could locate a clotheswasher or utility sink to get more clear water running through that section of piping, so much the better. In the meantime, don't be afraid to flush twice as a general rule.

FWIW, as a rule, I like angled joins rather than 90 degree joins, and I like to have a few clean-outs that are as easily accessible as possible. The extra few bucks on these changes are well worth it.


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## Curtis B (Aug 15, 2008)

Don't forget, clogged or unistalled vents can also cause slow to no water/waste movement.


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## HTG_zoo (Apr 18, 2011)

Thanks for the input.

Over the 110 feet, there is only 2 inches of drop and a sag in the middle of about 8 inches. This leads to water backing up in to the master bath tub when you run too much water in the sink. You can flush the toilet as many times as you want, it's not going to take down even a square of TP. There is a tub that is plumbed in and I can run water down it but it takes hour to drain a half tub of water. The pipes I want to replace with 3 in are currently 1 1/2. There are no cleanouts at that end of the house, but we have discussed installing one so that we could flush the lines periodically.

It sounds like I can just replace the weird plumbing that's down where with a fairly standard set up and be fine? That's such a relief. I'll check the vents too!


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## DaleK (Sep 23, 2004)

I would also wonder with the shower not being hooked up if there's a vent there that also isn't hooked up? Or no vent at all.


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## Harry Chickpea (Dec 19, 2008)

2" drop, 1.5" plumbing??? I don't know who installed that mess, but they need to buy a clue.


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## HTG_zoo (Apr 18, 2011)

I have a clue who installed it, and yes, yes they do need a clue...


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## plumbthumb (Sep 5, 2010)

Id try to get closer to 1/4" per foot.

what is the foundation level the pipe exits at and whats your joist height?

dont use any 90s. can cheat a hub 45 and fitting 45 to make a 90 with a wider run, but Id stay away from that if possible aswell.

if its in 1 1/2 and has a toilet connected to it.... there is probably not a vent, as your plumber/handyman was obviously not too bright.

use hangars every 6 feet under the house. Can just use generic strapping.

Never heard of 1/4 per 3'. is that an american code? Im canadian, dont know american code. seems quite iffy to me though, it is a small setup but Id rather be safe than sorry.


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## SteveO (Apr 14, 2009)

evening,
Code for 4" pipe is 1/8th of an inch per foot
code for 3" pipe is 1/4 inch per foot
So if you run 110 feet with 4 inche pipe you would need 110/8ths or 14 inches at a minimum.\as other have said start at the tank and see what you have for drop.
I would fix your droping pipes and see what that does. 
Steve


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## tiogacounty (Oct 27, 2005)

Current code in my area call for 1/4" per foot, 1/8" on 3 or 4" pipe only at the inspectors discretion. Tees are not allowed on drainage unless they are draining horizontal to vertical. When running horizontal to horizontal, you "Tee" into a line with a wye and a 45, never a tee. No logical reason to avoid 90s, "long sweep" 90s are required (where can be used). The OP needs a 3" main run to the bath, 1-1/2" to the sink and tub and 2" to a shower. Modern plastic pipe will effectively drain just about anything, regardless of how many fittings or length, if it is properly sized, installed, vented and supported. It is important that any future plumbers be aware that too much pitch can cause as much of a problem as too little. In a horizontal run serving a toilet, excessive slope will allow the waste from the toilet to separate. The solids will remain resting on the bottom of the pipe, while the liquid races past. The whole point of having the correct pitch is to allow the liquids to transport the solids to their "final destination"


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