The key factors for an optimal discharge pipe installation for a macerator pump are diameter, material, joint type, accessories, and supports.

Discharge pipe material could be copper, PVC, or CPVC, with  thickness to support the pressure discharge of the macerator pump, it usually is about 12 psig (pound per square inch gauge), but it can vary  for each manufacturer.  

The person who is going to install shall review the following technical specifications:

The recommended thickness for PVC pipes is SDR-21 (SDR is the thickness designation according to ASTM D2241 Std). About the joint type, a threaded end is the recommended  choice. Note that the bell spigot joint type usually used for gravity wastewater  is not an option  for a macerator installation. 

The next key factor to consider is pipe diameter. Macerator manufacturers normally recommend diameters from ¾” to 1½”. The ¾” diameter may be the cheapest alternative, but the high-speed flow increases the piping friction loss. Not only will velocity flow increase, but the pump’s power consumption will rise and there will be a higher risk of clogging the pipes. Even if a manufacturer recommends ¾” tubing, you may wish to consider the larger sizes as that will definitely reduce the risk of clogging. 

Another factor that influences diameter selection is the relative discharge location with respect to the macerator. You ought to consider the friction loss at the discharge pipe besides the pump's best efficiency point (BEP). The BEP (Best Efficiency Point) is the point at which the pump operates at peak efficiency,  with lowest energy consumption, and avoids unwanted force, vibration and noises.

The directional changes on the path must be covered with 90-degree long radius elbows (note: the 90-degree radius elbow can be replaced by two 45-degree long radius elbows) 

A good practice is to install an isolation valve at the pump's discharge to facilitate maintenance. The block valve prevents the water contained in the pipe from returning to the container. The block valve type options are: gate or ball. The ball type is more secure than the gate valve. 

When installing the horizontal piping it is a best practice to use a slope of 2% which helps with flow and drainage. 

The last key factor to consider is the support of the pipe, which helps transmit the stresses due to weight to the structure and keep it upright.

The separation between supports is a key factor. The distance depends on the diameter and the material of the pipe. Also, the weight of the content (water) and its temperature is something that needs to be considered. For horizontal runs below 50 degrees, the suggested support separation is indicated in the table below.

Table 1 Horizontal Support Separation


Support Separation (m)






For vertical sections, the recommended support separations are:

Table 2 Vertical Support Separation


Support Separation (m)





  • Dec 08, 2021
  • Category: News
  • Comments: 0
Leave a comment