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Question DetailsAsked on 1/26/2017

Cost to replace all pipes including water lines under slab foundation;

Single story house built in 1960s, galvanized pipes, water pressure not great, clogging on regular basis. Got an estimate from a plumber, seems way too high. (he ran camera) (32k) 2 bath, 1 kitchen, laundry line, water heater. (main sewer line from outside clean out to street was replaced about 3 yrs ago - we're good there) New piping needed in house and under slab foundation of house. I found estimates for repiping but not the additional water line repipe under a slab. We are in Southern CA. (91360) (would like the PEX piping)

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Ahhh - near my OLD stomping grounds, just over the hill.

You said main sewer line replaced from cleanout to street already - so not sure if you are talking replacing sewer pipe or not in house and under slab, but sounds like you are - per-foot cost similar to water piping, just a few $/LF more because of very slightly larger trench (and sometimes a foot or two deeper) and slightly more expensive pipe - but not a dramatic difference per foot.

On the sewer - I presume the sewer camera showed deteriorated pipe in general under the slab, not just one place that could be dug up and fixed. Probably cast iron, ductile, or maybe even clay tile in a CA 1960's house, so makes sense it might be time to replace it.

Below are some links on replacing piping - some under slab, some not - you said you found some info on the in-house repiping, presumably in the Home > Plumbing section of Browse Projects, at lower left ? So I won't address that - commonly a few thousand $ plus a thousand or two for plaster/drywall repair and repainting (which commonly means at least full wall/ceiling to match, sometimes entire room if picky on exact color match).

While redoing piping, consider if you need/want to replace any fixtures like faucets or sinks - cheaper to do them together than later.

Under-slab pipes, assuming normal slab-on-grade or basement slab, not pre-stressed or post-tensioned (which types would not have an open gap or fiberboard or rubber/asphalt filled perimeter joint at the foundation), generally around $20-50/LF depending on access, assuming around 3-5" thick slab and reasonable working headroom, not down on knees or belly, which drives the cost up 100% or so commonly. Remember - water line and sewer line will (or better be) in separate runs, 10 feet apart and with water at least 1 foot above the sewer elevation if I remember by CA code (so probably about 1-2 foot down for water and a foot deeper for sewer, so need separate trench for each.

Sometimes, especially with single story homes, the under-slab portion, especially for water, can be avoided by connecting into the in-wall piping at a convenient indoor point, then (watching out for buried utilities of course) run it in a new trench around one side of the house to connect into the existing water line - meaning potentially only one small hole in the slab (and foundation if not slab-on-grade) to bring the pipe up to the piping in the house, whereas the original run might be like mine - half way across the slab or more before it pops up.

Same thing can sometimes be done with sewer, but tougher because of the need to maintain proper slopes, so rerouting is normally only done in that case if the low point of the sewer line in the house is on the side toward the outside run to the street or near to a corner close to that, though I have been involved with reroutes (usually done only in crawlspaces or unfinished basements where pipe run hanging down is not a problem) where the sewer line was run a good portion of the way across the house but inside the house to the outside wall near the cleanout and down the inside of the wall there (or possibly in outdoor chase attached to the wall in warm climate like yours) to go outside - usually suspended from the first floor joists.

One other alternative - used a fair amount in your area - is pipe bursting (for the sewer pipe), where a hydraulic expansion tool is run into the sewer line and forces or "balloons" it open as a new continuous sewer pipe is put in - run from a pit outside (probably at the cleanout) to a hole in the concrete floor inside to connect it to the indoor plumbing. Eliminates almost all the cutting into the concrete slab. Generally not economic in unfinished basements or "peelable" (carpet and such) slab-on-grade houses, but can be economic as an alternative to taking up expensive flooring or flooring like tile that cannot readily be taken up or repaired to like-new condition, and certainly a LOT cleaner with respect to the in-house work, so sometimes done for that reason alone, especially in higher-end homes.

Discuss the situation and get bids from at least several Plumbers (maybe 5-6 if the bids are not coming in within a fairly tight cost range, because you will probably be seeing bids from the several thousand to $5000 range, all the way up to maybe $30-50,000 ! (Looks like he quoted you $32,000 - that is really high unless you are in a mansion and slab-on-grade - which I doubt because in 1960, as I recall, except for a very few larger homes in Westlake Village, pretty much everything was bsare scrubland or round 2200-3000SF tract homes.

BTW - PEX - buyer beware, the problems with connections and with the plastic pipe are NOT all history. And PEX underground - my recommendation is NO ! For underground I like seamless HDPE coil tubing, but schedule 80 PVC is OK. In your soil conditions I would NOT use copper. I don't feel schedule 40 PVC is strong enough for udnerground water pipe for domestic use - though fine for irrigation and such.

Here are links to a couple of similar prior questions with answers too, FYI -

Answered 3 years ago by LCD

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