High enough inlet water pressure from RO to espresso machine

Water analysis, treatment, and mineral recipes for optimum taste and equipment health.
Supporter ♡

#1: Post by nordics_please »

I'm getting ready to install a plumbed machine and the company's site specifies 43-72PSI for the incoming water pressure. I was told by my RO person that my system puts out 35PSI. I'm assuming this presents a problem, but can anyone speak to this specifically? Thanks!

Supporter ♡

#2: Post by Nunas »

If your RO system is the typical under-sink sort, then you will not have constant pressure, such as you have from the water mains. This is because the unit is driven by the incoming mains' pressure and is directed into an accumulator tank. When the system is at equilibrium (full accumulator and no water being drawn), the tank's pressure is approximately the same as the water main pressure, unless your system has a proper pressure regulator in it. However, as water is used, the pressure and the flow from an accumulator drop continuously until there are nearly no flow and nearly no pressure. This is especially noticeable if your accumulator is the typical small one supplied with most domestic RO systems.

So, if you use your system only for your espresso machine, or you ensure that your RO system is at equilibrium before using the machine, then you will probably have a fairly constant flow and pressure for the brief period and low use presented by an espresso machine. But, like the shower/flushing toilet syndrome, should water be drawn from the RO system while you are using it for espresso, then things would change rapidly.

But are you sure you really want to plumb an RO into an espresso machine? The typical RO system produces water in the order of 5 to 25 ppm TDS, depending on the mains water's hardness. I happen to use such water (~25 ppm from an RO system equipped with a bypass valve to add in some harness), and I'm quite used to it. However, you might be better off using your RO as a source of fairly pure water, to which you would add some minerals (lots of recipes here on H-B for that). Of course, this would preclude plumbing the output of the RO into the espresso machine, unless you added the minerals with a demineralization cartridge (which IMHO provides much more variable results compared to pouring into your reservoir a measured dose of a hardness concentrate solution, made up for the purpose).

Time to go make coffee! I hope this response helps you; rereading it, I fear it may confuse as much as inform :wink: .

Flair Espresso: handcrafted espresso. cafe-quality shots, anytime, anywhere
Sponsored by Flair Espresso

#3: Post by pcrussell50 »

Maurice, Southern California water is hard enough that even with RO or at least your typical home RO system, you will get nominally 15-30 ppm hardness anyway. The OP should verify for himself, but he should be OK on that front. Also, the typical home RO tank has enough volume that in shot making, he should not run it out of pressure unless he's feeding a big machine, pulling a lot of shots, or using the hot water tap on his machine to fill large containers of hot water. Even still, you can get larger accumulator tanks if he really plans on making a LOT of espressos in a hurry, and they're not terribly expensive. His mains pressure might be an issue. BUT he should check it first before writing it off. When I was in Southern California, both my houses the mains pressure was too high (7-8 bar) and had to be regulated down to something safer. If the OP is in this situation, (and my guess is that he is) then he ought to be able to regulate his RO pressure to what he needs for his espresso machine.


LMWDP #553

Supporter ♡

#4: Post by Nunas »

Peter, thanks for the info; it sounds like the water in SoCal is like ours, hard enough to drive nails into :lol: . At the moment, my bypass is completely off, and I'm still getting 15 to 18 ppm TDS. Sometimes it goes right up to 25. Your reply made me think of another aspect for the OP: the manufacturer's recommended input pressure and how that would relate to the RO system. Most prosumer machines require a regulator between the mains and the machine to drop the pressure. So, if he set the regulator's pressure to the lower end of the recommended values, then his RO system might even keep up to reasonably heavy demand, for a party, for example. Adding another accumulator is another good idea if the volume is high. I did that to my system because we have RO spigots in all bathrooms, the kitchen and the espresso bar. Plus, we use it in our humidifiers in the winter (no white powder issue) and home winemaking. We also have a permeate pump on our system, which increases the pressure greatly, lowers the amount of wastewater, and increases product water quality a bit.

nordics_please (original poster)
Supporter ♡

#5: Post by nordics_please (original poster) »

Thank you Maurice and Peter for your informative replies, and I'm happy you brought the quality of the water into the conversation as well. The machine is a Slayer, so no option to fill a reservoir with the RO and additives, unless I go down the road of getting their new optional accessory to draw water from an auxiliary tank. I feel like if I were to go to the trouble of that, I may as well just stick to the plan and plumb it. Regarding the quality of my RO, I've read here about adding re-mineralization cartridges onto the existing RO system. I'll speak with my RO company about that...Regarding water pressure- I definitely notice that drop in pressure when the RO is used heavily, and completely understand how this would affect the espresso machine. I do have a separate space with a small prep sink under which could have an espresso machine-specific system installed...maybe that's better than connecting to my existing RO?