Looking to buy a Slayer single group in LA and need advice on a good RO system. With the notoriously hard water levels in LA, the store I'm buying it from is recommending the Pentair BWS 100/5 system which costs about $2K - is this overkill or are there cheaper systems which work just as well?

That is a nice unit, especially if you know that you want to use the blending valve to get minerals into the water.

You can find some HB discussion about a similar system, the BWS175, here: Optipure BWS 175 System That system differs from the BWS 100 in that it has a calcite remin cartridge in addition to the blending valve, and it doesn't have the charcoal postfilter between the tank and the output line. Note in the post linked above, rrhaman said he was not using the blending function:

I did a little blending to 60ppm TDS to initially fill the tank, but now that its filled I closed the blending valve entirely and its been holding steady at ~70ppm as I make my daily drinks.

I'd suggest thinking about whether you really want to use blending for your LA water. ( https://www.ladwp.com/cs/idcplg?IdcServ ... stReleased ) If you try to meet Slayer's water recommendation, and blend in an alkalinity greater than 40 mg/L, you may end up with a chloride ion greater than 30 mg/L. So you might want to consider a cheaper simpler system that just uses a remin cartridge. It may not give you much mineral but would avoid that chloride corrosion risk.

Very helpful advice on a very complicated topic - thanks much!! Any recommendations on the simpler systems you mentioned with just the remin cartridge? My main concern is not damaging the Slayer, but at the same time having good tasting water ideal for espresso shots

Espressmyself wrote:Any recommendations on the simpler systems you mentioned with just the remin cartridge?

Can't help much here. Normally I'd recommend choosing one sold and supported by a reputable vendor of espresso equipment. But I looked at all the HB sponsors and it appears that the only one selling an RO system is Prima, and theirs is the somewhat pricy Optipure BWS175.

The APEC and the Homemaster systems use simple crushed marble or calcite cartridges for remin, which don't add much mineral but are nicely predictable and not prone to over-correcting even when water is being drawn from a cartridge that has been idle overnight. I think the iSpring and the BWT remin cartridges contain some Corosex or calcined dolomite, which may add a little more magnesium hardness and bump the pH more alkaline, but also may be more prone to over-correct. BWT reportedly advises that you flush the system before using it after being idle overnight -- kind of hard to do if you have the espresso machine on a timer that turns on and autofills before you wake in the morning.

The Homemaster full contact uses a couple check valves so that the water always goes through the remin cartridge on its way into the accumulator and through it again when going from the accumulator to the machine. Good idea, but still no guarantee that you can expect 30 - 60 ppm of mineral out of the system.

Some HB topics that may be useful:
Homemaster RO water + remineralization
Reverse osmosis water system recommendation?
Yet Another RO + Water Remineralization Setup Question
Remineralized RO water for new espresso machine
BWT Bestmin for remineralization

I know the Go Get 'Em Tiger shops all use "Living Water SoCal for all our R/O systems."

I was going to install one but short on space and just have a 3m Esp124 with an added carbon filter off of it.

Living Water uses a 1:1 RO membrane instead of the lower efficiency membrane plus a permeate pump used by Homemaster. It seems like a much more simple setup. I had issues with the premeate pump in my Homemaster and ended up removing it, but I believe most people don't have any issues.

As Pat mentioned, the advantage of the Homemaster over Living is that the former uses a remineralizatiion double-pass system that in theory can get you to 30-60 mg/l. In real life I get an average of 20ppm reading with my cheap TDS meter. Anyway, I am planning to change the Homemaster membrane to the same one used by Living (Pentair GRO-75) and this way I can enjoy both worlds.

I think that if I had to do it again I would buy the Living system. They also use generic filters (Omnipure). If you ever end up getting it I would love to know the real life TDS reading.

katkat wrote:In real life I get an average of 20ppm reading with my cheap TDS meter. Anyway, I am planning to change the Homemaster membrane to the same one used by Living (Pentair GRO-75) and this way I can enjoy both worlds.

I think that if I had to do it again I would buy the Living system. They also use generic filters (Omnipure). If you ever end up getting it I would love to know the real life TDS reading.

Why not take complete control and give up concerns about how the cartridges are working?

Espresso Cart - Goodbye Plumbed In

With your RO how do you know you are in spec? [From current Slayer manual v7.1 Aug 2022]
pH: 7-9
Total Hardness: 2-6 grains TDS: 50-200 mg/L
Alkalinity: 40-100 mg/L
Chloride: <30 ppm
Silica: <10 ppm
Chloramine: <.1 ppm
Chlorine: <.1 ppm

A number of Slayer owners use this. Make the Hardness and Alkalinity as you please and stop the worry. One of the main features of the system. As I tell others, it takes me longer to distract my curious cats than it does to make water every 10-12 weeks. It's not a hard process.

Note Slayers made after Jan 2020 probably don't need the pump or accumulator as the Rotary pump can draw from a tank.

I did consider this initially, but due to the layout in my kitchen and available space, was not the ideal option. I do like the flexibility it gives you, but in the end have made the decision to go with the Optipure system recommended by the dealer. He has installed dozens of these throughout SoCal and swears by their effectiveness. Kitchen is almost ready for the install - I eagerly await!