Having worked in the water treatment industry for over a decade, the most frequent question I get isn't about the effluent quality, but about the pressure gauge reading. Many people panic when the pressure is high, and think it's fine when it's low. Frankly, both of these mindsets can easily ruin the equipment. The pressure of a reverse osmosis (RO) system isn't a fixed number; it's linked to water temperature, raw water TDS, and membrane type, but there are a few strict ranges. If these ranges are exceeded, you need to investigate.
Reverse Osmosis Equipment
Don't arbitrarily adjust the high-pressure section; increasing it will burn out the membrane.
The inlet pressure of an RO system is generally controlled between 1.0 and 1.5 MPa. This range isn't something to be arbitrary. Too high a pressure puts excessive pressure on the membrane; while the flux increases, the membrane life is halved. I've seen too many customers increase the pressure to increase the effluent output, only to have the membrane fail within three months. If the high-pressure pump outlet pressure consistently exceeds 2.0 MPa, you should consider whether the pretreatment is inadequate or clogged.
I have a true story about this. Last year, a food factory east of Xi'an contacted us in March 2024. saying their reverse osmosis system had lost 40% of its permeate production in less than a year. When I inspected it, the pressure gauge reading was 1.8 MPa, but the concentrate pressure was only 0.3 MPa. The front-end security filter was clearly choked, and the membrane was scaled. I told them the membrane was essentially ruined, and replacing the consumables would cost over 20.000 yuan. They were horrified. Later, they replaced the entire system with our DIEN's equipment, redid the pretreatment, and now it's running stably, with permeate production restored to over 95%. You see, pressure isn't something you can just judge by looking at a gauge.
Low pressure is the real killer.
If the concentrate pressure is below 0.5 MPa, it indicates excessive system resistance or a pump problem. I can't say for sure, as different membrane elements have different tolerance ranges, but there's a general rule—if the concentrate pressure is below 30% of the feed water pressure, the system is basically just barely holding on. Many people ignore the concentrate pressure and only focus on the feed water, only realizing the problem when the permeate production drops, by which time the membrane is already irreversibly damaged. To put it bluntly, the most expensive thing in the water treatment industry isn't the equipment, but operating blindly without looking at the data.
Reverse Osmosis Equipment
Pressure: You need to look at all three numbers together; focusing on only one is useless.
Some people ask me why there's such a big price difference in reverse osmosis equipment. I just want to ask, does the system you bought have inter-stage pressure drop monitoring? Feed pressure, concentrate pressure, and inter-stage pressure drop—you need to look at all three together. An inter-stage pressure drop exceeding 0.07 MPa indicates that the membrane in that stage is starting to clog. Cheaper systems cut out pressure protection and online monitoring; you save money when you buy, but it's a nightmare to run. Our DIEN equipment comes standard with real-time pressure monitoring and automatic protection; abnormal pressure triggers an alarm and shuts down immediately, so you don't have to stare at the gauges every day. This isn't high-tech; it's just doing the job properly.
Pressure management in reverse osmosis equipment is ultimately about diligence. If you're too lazy to look at the data, even the most expensive equipment is useless. How long has it been since the pressure gauges on your factory's RO system were calibrated? Tell me in the comments, and I'll help you assess it.
