Is pump/grinder system in new house a red flag?

May 6, 2023 4:41 PM

I'm considering putting an offer in for a house, and was just told by the seller's agent about the house's pump/grinder system. Is this a red flag?

Location is Central Austin. I've lived in this neighborhood for many years and it is a flatter area, and I've not heard of a pump/grinder system being needed in houses around here. The house is a back unit, built as ADU and now sold separately, built ten years ago. The agent said there's not enough drip to the sewer line so they needed the pump/grinder system.

Should I be concerned? I'm just surprised this location would require a pump/grinder system as it is not on any hill, and it makes me question potential issues to come.

posted by monologish to Home & Garden (7 answers total)

There are almost definitely people who know more about the plumbing practices in your area, but I have a few "general knowledge" bits of info and speculation which may be helpful.

Standard sewer lines are pitched 1/4" per foot of run. (With the outlet of the house being the high end and the sewer in the street as the low end.) If there is a main house on the front lot and the ADU was added later, it's possible that the ADU would have had to have been elevated significantly to make sewage flow via gravity to the existing line for the front house and or the added sewer line would have been too close to the surface by the time it reached the ADU while maintaining pitch/slope.

I'm assuming that this pump/grinder is what is normally called an ejector pump. I have never seen a "whole house" ejector pump, but it definitely will be another mission critical electro-mechanical device to maintain, in the event of a power outage you would not be able to flush the toilet more than a couple times etc (w/o having a generator or battery backup to run the pump)

It might be good to get the opinion of a tradesperson. Obviously, a gravity drained sewer system is preferable, but whether or not this is a deal killer for you is something only you can answer.
posted by Larry David Syndrome at 6:10 PM on May 6, 2023 [4 favorites]

I've lived in Austin a long time, and had to google what that system is. It sounds like they made at least one major compromise to fit the building in, and I would wonder if they made more.

If you decide living very central is worth it, set aside funds for repairs and mess. And definitely have a backup plan for our extended power outages.
posted by mersen at 6:49 PM on May 6, 2023 [1 favorite]

It's not a red flag per se but it is one more thing you'll want to get checked before you buy and will have to pay to maintain and keep running.
posted by gible at 10:14 PM on May 6, 2023 [1 favorite]

If you live here you'll want to know who are some good people to call if this breaks down. I would find some of those people now, and try to pay one to come along for this on the inspection. During this, get a sense of what the downsides are relying on this pump and if they can be mitigated.
posted by away for regrooving at 11:19 PM on May 6, 2023 [1 favorite]

There is a grinder and pump in a facility where I am a director. We have definitely had major problems with backups, and lots of long conversations about exactly who is responsible for the problems- the downstream side of the plumbing, which is also not pitched steep enough, or our facility. Those conversations are about, of course, who should pay for repairs and damage. We keep it maintained.

With this experience I'll say: the best thing is to not need a pump and grinder to start with. Plan on having raw sewage backups into the house. Or just walk away, which is what I'd do.
posted by Dashy at 5:23 AM on May 7, 2023 [1 favorite]

We looked into adding a bathroom that would've required an ejector pump because of the grading where we wanted it in the house. Three separate plumbers recommended against the entire project. Every single one of them said that they'd never seen a project where a pump hadn't failed repeatedly. All three said that they had regular jobs where the same pumps needed to be replaced every couple of years. No bueno.
posted by dancinglamb at 6:10 AM on May 7, 2023 [1 favorite]

Grinders for ADUs are actually pretty common. It's honestly why I think ADUs are a freaking terrible solution for adding housing and why giant firms should mostly build houses. Yes, they are a bit of maintenance and it is a pump and grinder so you should expect it to fail eventually so budget for that. Other than that (and the thought of it being kind of gross) it's really not that big a deal. Skip this one if you want, but if you are looking at backhouses, expect some kludgy solutions.
posted by The_Vegetables at 7:24 AM on May 8, 2023