The four costs, not one
A watermaker has a purchase price, an installation cost, a running cost and a consumables cost. The brochure covers the first. The other three are where boats differ by thousands of dollars, and they are the reason two owners with the same unit can have completely different opinions of it.
| Cost | What drives it | Can we source it? |
|---|---|---|
| The unit | Output, pump technology, framed or modular, auto or manual controls | Yes — indicative figures in our table |
| Installation | Through-hulls, brine discharge, wiring run, mounting space, joinery removal | No — entirely boat-specific, must be quoted |
| Running | Watt-hours per litre × your daily litres, or fuel for a petrol unit | Yes — computed from rated draw and output |
| Consumables | Prefilters, membranes, pump service kits, pickling chemicals | Partly — sizes are published, prices need a dealer |
We publish what we can source and flag what we cannot rather than filling the gaps with estimates.
What the units themselves cost
Across the systems we table, indicative pricing runs from roughly $4,400 for the cheapest portable AC unit to around $15,000 for a large framed system with automatic controls. Those are list or dealer-conversion figures excluding freight, duty and installation, so an Australian landed price reads higher. They are useful for ranking, not for budgeting.
| System | Power | Output L/hr | Draw W | Wh per litre | Price |
|---|---|---|---|---|---|
| Portable AC 75L Rainman | AC 240V | 55–82 | 1,250 | 18.2 | $4,402 |
| Modular AC 75L Rainman | AC 240V | 55–82 | 1,250 | 18.2 | $4,522 |
| Portable 24VDC 55L Rainman | 24V DC | 45–61 | 600 | 11.3 | $4,898 |
| Portable 12VDC 34L Rainman | 12V DC | 26–37 | 400 | 12.7 | $4,898 |
| Modular 24VDC 55L Rainman | 24V DC | 45–61 | 600 | 11.3 | $5,053 |
Cheapest to buy is not cheapest to own. Every one of these uses a conventional high-pressure pump, so the energy per litre is several times that of an energy-recovery system.
What installation adds
We do not publish installation quotes, because the honest range is so wide it would mislead you. A modular system going into an empty machinery space on a boat that is already hauled out is a different job from retrofitting a framed unit into a finished interior where the joinery has to come out and go back.
What you can control is how the quote is structured. Ask for the unit and the labour separately, and ask specifically whether these are included:
- The seawater intake: a dedicated skin fitting and seacock, or a tee off an existing one (a tee is cheaper and a common source of air problems).
- The brine discharge route and its through-hull.
- Cable, breakers and any DC distribution work — undersized wiring is the most common cause of a system that underperforms from day one.
- Commissioning: pressure test, product-water TDS check, and someone showing you the flush and pickle procedure on your boat.
- Making the filters, gauges and flush valves reachable afterwards. This costs a little now and a lot later.
What it costs to run
This is the number nobody quotes and the one we built the site around. Energy per litre — watt-hours per litre — multiplied by your daily litres tells you what the watermaker takes out of your day.
A four-person crew at 25 litres a head needs 100 litres a day. On the most efficient system we table that is about 370 Wh, roughly what one 400 W panel makes on a fair Queensland morning. On the least efficient it is close to 2,000 Wh, which is more than most 12 V house banks can spare without running the engine. Same water, five times the energy.
| System | Power | Output L/hr | Draw W | Wh per litre | Price |
|---|---|---|---|---|---|
| Zen 30 Schenker | 12/24V DC | 30 | 110 | 3.7 | $6,300 |
| Zen 100 Schenker | 12/24/48V DC or AC | 100 | 400 | 4.0 | $9,600 |
| Ventura 150 Deluxe Spectra | 12/24V DC | 24 | 108 | 4.5 | $6,000 |
| Ventura 150 Connect Spectra | 12/24V DC | 24 | 108 | 4.5 | $7,400 |
All four use energy recovery: the brine's pressure drives the inlet instead of going overboard.
If you run a generator, convert that to fuel. If you run on solar, convert it to panels and battery you would otherwise not have needed. Either way it is a real recurring cost, and over a decade of cruising it can exceed the difference in purchase price between an efficient system and a thirsty one.
Consumables over a decade
Prefilters are the routine cost and need replacing more often in silty, plankton-rich or harbour water than in clear ocean. Pump service kits come up periodically. Membranes are the big-ticket item, but they are also the one most often replaced unnecessarily: a membrane that is fouled, not failed, can frequently be recovered, and low output usually points at feed flow, pressure, temperature or a blocked prefilter before it points at the membrane.
Before you buy, ask whether the membranes and prefilters are standard sizes you can source from any supplier, or proprietary parts you can only buy from the manufacturer. That single answer changes your ten-year consumables cost more than the sticker price does.
How to compare two quotes properly
- Get both as a landed AUD figure including freight, duty, GST and commissioning.
- Divide each price by rated output to get dollars per litre per hour of capacity.
- Multiply each system's Wh per litre by your real daily litres to get the daily energy cost.
- Ask what a set of prefilters, a pump service kit and a membrane costs for each.
- Ask who services it in your state, and whether they hold parts or order them in.