RO Unit Low PSI

[mike31154]

What's your water source, city or well? If city, check your plumbing for a pressure reducing valve. Should be just downstream of the main water shutoff for your house. It might be adjustable to get you a higher pressure.

Not sure about running your unit at such a low pressure. Probably no damage, but your output will be agonizingly slow and probably somewhat inefficient. 21 psi is pretty pathetic for pressure if it's from the city.