Heck, I don't care if you are a guru or just someone with more sense then me.

Our house was built down hill - basically half way down a hill. So front yard is uphill and back yard is way down hill. The sloe was cut into and a pad made. Piers were used for the foundation when poured.

Recently (maybe last 2-3 months) we have noticed water on our back porch by our fireplace. It is running from the house/chimney corner out to the yard. It is wet, not really "running". This happens after many days of rain. Couldn't find a leak on roof, inside house seems ok. Just had a roofer out, it seemed worse after last weeks rains, and he couldn't find anything - but is coming back later this week to fix some things he said could use being cleaned up (flashing, etc).

Anyways, there is like a salt line build up after the water dried out. The roofer thinks it may be coming up and not down. I don't see any foundation cracks, etc. Thoughts??

Was that patio a second pour to the slab? We have this issue after heavy rains with water coming up between the house and driveway.

It was all built at the same time and am pretty confident it was one pour.

I poured concrete for a living many years ago. Because your slab is built on a steep grade, hydrostatic pressure is causing water to seep through the concrete. Concrete is porous so there’s not necessarily anything wrong with the slab. If it’s coming up in an area where no damage to floors will occur, it will stop when the water table lowers and it wouldn’t be a big deal to me. If it’s inside in the living space, vapor barriers can be installed outside but the labor will be expensive. A vapor barrier coating can also be applied on it but that traps the water inside the slab which could cause it to seep up in a living space.

Dig a sump on the uphill side and put in an automatic sump pump that discharges downhill from the house.

I had this on a house i had.

Check your chimney cap including the masonry on top of the chimney. Also, the shoulders of the chimney will let water in and may need to be redone.

Silly question potentially...do you have a water softner?

yes

Did check all of that today. It all seems to be intact. THey are coming back to do a water test (basically running a hose up there for a period of time).

Yes. Was thinking I may need a french drain of some kind.

Well hoping it is not a big deal and never affects living area. Obviously going to need to keep a close eye on it.

The salt makes me think you might look around it for a leak. It's crazy how and how far water travels...also make me think it's not ground water, it's water you've treated and you have a leak somewhere. Time to call a plumber if you can't figure it out.

I may call one, but I sure can't figure out where it would come from. All of the water lines are pex through the attic, and there is no water on that side of the house. I know it could travel, but the only source (I think) would be a sprinkler - and those have been off for a bit.

The salt runs right through the concrete with the water from the ground. I'm 99% sure it's just from the rain we've had after reading all your posts.

I believe Trapper is correct. The water is percolating right through the slab. I run into problems like this pretty regularly when I build pools in yards with big elevation changes. The only sure fire way to fix it is to never give the water a chance to get under the slab. Intercept the water and reroute it before it makes it under your house. Digging is labor intensive but the materials are pretty cheap. This is a link to the pump I like to use. I haven't found anything that last longer.

https://www.amazon.com/gp/aw/d/B004QVPGHG/ref=ya_aw_od_pi?ie=UTF8&psc=1

Very good point and it sucks.