One of the greatest variable costs that a well owner has is the labor paid for the installation and removal of their well pump and motor. To minimize this cost over time, it is important to choose drop pipe that will last while also considering the ease of installation and removal.
At RC Worst & Company, we offer three different types of drop pipe for water well systems. I am going to highlight some of the pro’s and con’s of PVC, Galvanized, and High Density Polyethylene (HDPE) pipe. HDPE pipe is commonly known in the industry as Poly Pipe. Hopefully, learning the differences will help you make an informed choice for your application.
The main factors to consider are weight limitations, depth limitations, flow restriction, water composition, ease of installation, and ease of removal.
For those unfamiliar with the term friction loss, it is the loss of pressure or “head” that occurs in a pipe due to the effect of the fluid’s velocity near the surface of the pipe. For every foot of pipe, the PSI (pounds per square inch) lost in Galvanized or PVC is about twice that of Poly. For illustration, here is the friction loss of liquid moving at 25 gallons per minute through 100 feet of each:
1” galvanized: 28 PSI lost or about 64’ of head lost
1” Poly: 13 PSI lost or about 30’ of head lost
1” PVC: 29 PSI lost or about 66’ of head lost
In considering depth limitations, Galvanized is capable of going to almost any depth. In fact, the check valves used will normally be the first thing to limit the depth in the system. Also, keep in mind you need to know the limitations of the other fittings that you use. For example, a commonly used brass check valve is rated for about 600 feet and a ductile iron check valve is rated for about 1,500 feet or greater. PVC Schedule 120 is generally limited to a motor no greater than 1.5 HP on 1” drop pipe and a maximum depth of 650’ and generally limited to 2.0 HP on 1.25” drop pipe and a maximum depth of 520’. We, at RC Worst, do not recommend installing Poly pipe at a depth greater than 100’ as it is hard to install, and even harder to service.
Galvanized pipe is the best in higher pressures with 1” Schedule 40 rated to about 2,100 PSI and 1” Schedule 80 rated to about 3,500 PSI. PVC comes next with 1.25” Schedule 120 rated at about 600 PSI. Poly Pipe has the lowest pressure rating of about 250 PSI. For deep installations, make sure all the check valves and any other fittings can also handle the operating pressure.
Galvanized pipe is very durable in normal water conditions and will last on average 15 to 20 years. It is zinc coated to prevent rust and corrosion, however, water that is highly alkaline or acidic will corrode Galvanized pipe. PVC and Poly pipe will hold up very well in harsh water conditions.
When it comes to installation, Galvanized and PVC pipe are simple, predictable, easy to install, and easy to service. PVC pipe is also lightweight. Poly Pipe, as I mentioned previously, is not recommended at a depth below 100’. Installation and service at a depth greater than 100’ can create a safety risk. It is simple, predictable, and easy to install & service at shallower depths.
Hopefully, this blog has given you some good information on choosing the right type of pipe for your system. You can also check out our video titled “Water Well Drop Pipe Selection Guide” on the RC Worst YouTube Channel or give our experts a call at 855.329.4519.