The Problem with Overhead Drain Lines for Water Softeners

A few years ago, a long time customer decided to purchase new twin softeners from my company for his new RO system. The RO water was to be used as boiler makeup water as well as a source of high purity water for their homogenizers.

The equipment room where the softeners and RO were located did not have any floor drains. There was a small pit that collected water or any other spills and a sump pump that was routed to a large overhead drain line.

Just before the softeners arrived, I received a call from the plant engineer asking me if it would be OK to route the softener drain lines to the overhead line which was located 10 feet above the floor. Instead of checking with our engineering department, I called the softener manufacturer sales rep (who I later found did not have a clue about proper engineering design) and was told, “No problem”.

The softeners were installed and I soon received a phone call from the Maintenance Superintendent who informed me that the softeners were leaking anywhere from 4 to 6 ppm hardness after regeneration. He wanted to know why this was occurring when the old softeners always showed zero to 1 ppm hardness. The old softeners were much smaller however they were located in the boiler room which had a floor drain which collected the regeneration water.

I decided to call my engineering department (which I should have done in the first place). The design engineer who previously worked for Bruner and later Marlo and had a significant amount of knowledge about softeners, was able to quickly diagnose the problem. He explained that based on the inlet pressure, the softeners were designed for a brine draw flow rate of 0.5 to 1.0 gpm per cubic foot of resin to insure optimum brine/resin contact time and regeneration efficiency. He calculated the brine flow was less than 0.5 gpm and the brine was basically channeling through the bed because of low flow.

We scheduled a meeting with the customer and they were obviously upset because I gave them bad information. I did explain that the softener company assured me there would be no problem with the overhead drain line. My design engineer was with me and quickly offered an option that they install a 3-way valve which would direct the backwash and fast rinse water flows to the overhead drain line but would be programmed to direct the brine draw cycle to the sump pit located in the floor. The sump pump could handle the much lower brine draw flow rate without flooding the equipment room floor.

This recommendation solved the problem as they noticed less than 1 ppm hardness even at the end of the service run.

Lesson learned: Make sure you know who you are talking to when you ask for help solving a problem. Not all salespeople are poor technically but there are some who are.