I would imagine that it potentially could rot. The issue of odor though I'm not convinced of.

The pressure of a full basin of water should exert enough pressure on the sides to limit the exchange of gas (odor). If you extend the padding outside of the size of the rubber liner it may be a problem.

I know my pond never smelled. Then I drained it and pulled the liner up. WOW!! That smelled for a bit. But never when the pond was at full pool.

Also, remember modern day carpet is typically either 100% nylon or 100% polyester fiber (or a combo of both). About the only thing that could rot would be the actual backing.

I used the expensive underlayment on previous ponds (with a small section of carpet underlay) and used carpet for my latest pond. Both are very good. When I tore out the old pond I found after 4 years that the carpet underlayment had not broken down at all. The geo-whatever they call it looked brand new. The upside is when I swim in my mewer pond I can feel the cushiness of the carpet underlay and I love it. There is no bad smell with my pond even though it has rained for 2 months straight. So no worries on carpet underlay. Hope that helps.

Works perfectly. I have a second (out of site) utility pond where some of the rug is exposed. It is 4 years now and it looks exactly like when I put it down. I used thrown away rugs from a rug dealer/installer. They have tons of it and are happy to get rid of some of it and they save one extra dumpster load. When I need to find potential leaks, the newly exposed rug is fine also. No rotting, no smell, can't beat it. I treat the utility pond poorly and occasionally the liner has curled down and allowed the pond to overflow and essentially fill the hole and rug completely in water with no ill effects on the rug.

Thanks everyone! I think I will go with the carpet. :) One of my friends, dads used to have a carpet business and has horder a lot of carpet. I'll just make sure it's a color that will match my plants. LOL

I am excited! The pond is coming along!

-First time ponder, long time fish ;)

Liz

About the EPDM... I used roofing EPDM with good success. Just haven't had a problem. (I also put down used carpet as the underlayment).

30'x40' is a pretty size-able liner. You might just think of getting a full size roll of EPDM roofing. I believe it comes in 20' and 50' lengths (you said you're using 40') when in either 45mil or 60mil and 20' WIDTHS, though maybe wider depending on the manufacturer.

Either way, it is heavy enough that you aren't going to want to pay for shipping... no mail man or UPS is going to be able to handle something that large.

I had the building supply house deliver and use their spiderlift to place if right over my hole. This is the way to go if you're using such a large piece of EPDM.

Good luck.

Thanks pondbucket! I asked the local ponds shops and got quotes on ordeing a piece that size. Both were around $900 total. So I found a website pondliner.com and ordered it through them today. It came to $760 with shipping. Shipping via a carrier. Problem is the 20' width wouldn't work without seeming it together. Not something I want to do.

Today I purchased a 7200 GPH pump, a 15" diameter tube three feet long to place it in. The pond guy told me by poking holes in the tube and filling it with some sort of BIO pellets (or something like that I can't remember) it will help filter the water and keep the pump from getting clogged with muck. That pump will run the water to the waterfall. I also purchased a small skimmer with a 1250 GPH pump that will move the water from the top to the bottom. I was able to get all the hoses and PVC attachments I need. I am really excited!!!

I also found out that here in Utah you can get a $10.00 permit to go get your own rock from public lands through the geological survey folks. They also give you a map of the state and tell you the type of rock that can be found where. So we are going to go do some rock hunting. This should help with costs ;)

I think about two weeks from now we should have it filled and running.

WOW! Keep us informed as you go...and take lots of work in progress pics, you'll enjoy looking back at them, and you can post them here too!

Carpet is definitely okay, I suspect your pond guy is doing his job, selling you stuff.
Make sure you know what size liner you need, plant shelves take up liner length when calculating length and width I've used azponds dot com they will cut and ship exactly what you need, prices are on the site. Good luck.