I'm renovating the bathrooms on an old house I purchased. The house sat empty for a year or two and I have no idea of the condition of the waste line on city sewer. Turning the sink on or putting a hose down the line with high volume and the water flows perfectly fine, but the idea of toilets flushing has me wondering if it makes more sense to get a toilet that has 1.6 GPF instead of the standard 1.28 GPF? I realize if there is an actual issue, the extra bit of water probably won't help all that much, but it still seems like a smart idea to have that extra water.

Toto Drake 2-piece looks like a quality toilet that is reasonably priced at 1.6 GPF versus the usual Kohler's at big box stores that are all 1.28 GPF?

All the old cast iron in the house has been replaced with PVC so that part is all set, its the line between the basement and the city sewer I'm concerned about.

Only one way to find out if the line flows well or not, and that's to hook a toilet up and start using it. Does it make sense to get the 1.6 GPF one?

I could have someone come camera the line I suppose too or get a camera and attempt to check it out myself.

  • I'd skip Kohler's simply based on the one that had clearly been seen to be cracked by quality control which they shipped anyway, that I had to return.
    – Ecnerwal
    Apr 12, 2023 at 0:56
  • I have had 2 Kohler toilets for the last 10-15 years and I’ve never clogged them once. The old toilets before would clog regularly. It does seem that the quality has slipped especially with the bowls now that include the slow close seat and all. Guessing I’ll need to spend that extra bit to get the same quality since the ones I have were also the slightly better bowls. The Toto’s seem to be praised all around so they have my interest.
    – RocketManZ
    Apr 12, 2023 at 3:43

2 Answers 2


There's no need to waste an extra third of a gallon per flush. Sewage is about 90% water anyway. If the pipe won't run solids, it won't run solids with a bit more water, either. The solids will hang up and the water will run away.

Take a look at it or have it preemptively cleaned if you like. It's probably fine, or perhaps it's falling apart and you'll get to replace it with plastic. Are there large trees on/near its path?

  • Fair all around. I may do some tests and see if I get any backup. Or just buy a bowl and start using it. I need to find out one way or the other. The Toto toilets supposedly are top notch quality above many others in the sub $300 price point, so I’m considering their toilet brand regardless of GPF. I’m going to ask my DIY buddies and see if anyone has a sewer line inspection cam too.
    – RocketManZ
    Apr 12, 2023 at 3:40

If you're worried about the state of a ~100 year old (you didn't say exactly how old the house was) cast iron sewer pipe, spend a couple of hundred dollars and have a sewer line cleaning company come in and do an internal 'scope inspection.

My home's sewer line to the street is 70 years old and has no issues, so I have never had a need to get it inspected.

My son's house, on the other hand, is over 100 years old and the sewer line has been rerouted from the back of the house to the front street when the house was moved off septic to public sewer. This 180 deg turn is causing problems.

  • Great point. I've owned homes well over 100+ years and to my knowledge the lines were original, so your right its definitely possible its fine, or not. The issue with this home is the line is older, but it also sat without water going down the line for a year or two, so that has be wondering if the pipe going from being regularly wet, to being dry could have caused it to splinter or something like that. I may either get a sewer cam and do an initial inspection myself, or have someone come and do a pro job. The DIY in me can't help but try to push a camera down there first and have a look.
    – RocketManZ
    Apr 12, 2023 at 22:08

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