SDR35 (PVC 3034)
Thu, Aug 2, 2018I was at Lowes today to pick up fittings for the running the remainder of the pipe that will connect the septic tank to the drain field. This should have taken about 15 minutes, but I got myself all kinds of confused and was there for a good hour.
Not all PVC is the same. I was already aware of the differences between Schedule 40 vs 80, and when to use ABS or CPVC, etc, but I was getting thrown off by a PVC classification Lowe’s had simply branched ‘Drain and Waste Pipe’. Getting on their website, the description showed this was PVC 3034.
After much research, here is the thing: PVC 3034 and SDR35 are the same type of pipe. Depending on where you are shopping, they may be labeled one or the other, but know they are the same thing.
Additionally, all these different PVC types are designed for different things. Schedule 40 is for higher pressure applications (our potable water will probably use some schedule 40 somewhere). ABS and schedule 80 would be for non-pressure situations. In other words schedule 40 is stronger, but don’t assume this is the best for your application!
Remember these pipes are going to be buried. Vehicles may drive over them at some point, large rocks will be butted against the pipe. They are going to be subjected external forces. For this reason, we want the drain pipe to have some flexibility. If the ground settles in a certain way, we don’t want the pipe to crack, but to bend. Schedule 40 (and in my opinion, 80 too) is more likely to crack with even a little flexing. PVC 3034 was designed to be more flexible for buried applications.
At least that is what the manufacturers say. You’ll will find lots of debate online whether to use schedule 40 vs PVC 3034. Ultimately, we went with the manufacturers (and our local plumbing supply shop’s) advice and used PVC 3034 for our septic system.
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