Material for Bottom Drain Pipe

[garywalker]

Is there any reason why ABS should not be used instead of PVC for the pipe from a bottom drain? ABS is less expensive and more readily available in the 3 and 4 inch sizes (Home Depot, Lowe's, etc.).

Gary

[paladin_k2]

The issue with ABS is the reliability of glue bonding of the fittings to the pipe. ABS glues DO NOT actually solvent weld the fittings to the pipe so it is possible for the connections to pop if stressed.

If you look closely at PVC fittings you will find fittings that satisfy the Schedule 40 pressure pipe standard and these fittings have almost twice the surface bonding area as the fittings that are held in seperate bins for what is called DWV applications.

It can be complex to switch from ABS to PVC when you try to use valves and other fittings.

The only place I used ABS fittings in my big pond install was in the bottom drain cones of the sedimentary vortex and the media chambers. And all those lines were encased and reinforced with concrete. All of the primary flow piping was constructed with PVC and good solvent welded joints.

Here is a link to a diagram showing the chambers and their incoming valve plumbing: DIY filter systems?

[luke frisbee]

bloody good post there paladin

[garywalker]

Paladin,

Thanks for the very informative answer. I will use PVC for the pipe and joints. The bottom drain itself is ABS but I will surround it and its connection to the PVC pipe with concrete so the joint should hold.

[paladin_k2]

Just as an added note, the transition from ABS to PVC can be tricky and unreliable if not assembled properly.

In larger pipe sizes, such as found in 4" bottom drain outlets, the recommended approach seems to be to use a rubber coupling with external stainless steel pipe clamps that fit snuggly to both the ABS of the bottom drain and the PVC of the outflow pipe. The rubber boot provides the watertight seal and then when it is nested in a concrete footing everything is sturdy enough to meet the 30+ year durability test.

Here is a picture of a W. Lim bottom drain bowl all connected up and just prior to setting the concrete support collar and footings of the final pond construction. Note the Stainless clamp bands on the rubber coupling:

[garywalker]

It occurred to me that it may be feasible to use only PVC in the bottom drain as well as in the pipe. I am considering using a 4 x 4 x 4 PVC tee as the primary drain component. One end would be attached to the 4 inch drain pipe. The other end would have reducers to 1 inch to attach to a 1 inch PVC pipe for incoming air. The air would continue into the tee in 1 inch PVC then turn upward via an elbow joint and an additional length of pipe. I am trying to identify an appropriate item to use for the dome. I am thinking of drilling a hole through the center of the dome and inserting the end of the air pipe into it, secured with PVC glue. That way there would be no "legs" on the dome to restrict the water flow into the drain. Some sort of diffuser could be attached to the top end of the air pipe. Any comments?

Gary

[MCA]

suggestion use a 6x6x4 sanitary Tee as the sump. You can get them a Lowes.

see message 8 in the following thread.

venturi, where and how to install in pond


of course you pour concrete all around the BD and around the drain and air pipes. Never expect the pipes in the floor to take the downward pressure of the pond water.

[koiczar]

When you talk about the use of ABS vs PVC schedule 40 in underground installations - keep this fact in mind as well - PVC is a solid material poly vinyl chloride, where as ABS is designed for drain,waste and vents (DWV) and is a foam core pipe. If you want to use ABS 6-8 feet underground, you could end up with a pipe that becomes misshapen over time due to weight of soil/compaction and it could even collapse (although this would be extreme, yet possible). When we build a pond, EVERYTHING THAT GOES UNDERGROUND IS PVC! ABS and PVC can be glued together with no problem, just make sure you use the correct glue, such as Christie's Red Hot Blue Glue. It's designed just for this purpose. I don't however recommend using ABS couplers. There just isn't enough "shoulder" to make a good long lasting and solid connection.

Mike

[garywalker]

MCA,

Thanks for the input. However, the problem with a 6x6x4 sanitary tee is that it requires sealing the bottom 6 inch opening as well as making a hole in the side of the tee for the air pipe. That would have to be a precise cut to prevent leakage even with PVC cement. With the 4x4x4 no additional holes are needed and the two ends of the tee are sealed with PVC fittings and cement, so no leaks.

Gary

[garywalker]

Good points, Mike. Thanks.

Gary