Depends on the technology utilised
Firstly, you state it utilises water, of any type, of a refridgerator-esque size (how long is a piece of string? How big is a refridgerator?). The first concern that immediately changes it's viability is it's environmental impact, not it's cost.
Does it permanently consume water? IE would it deplete water reserves? Even in small amounts, this would make water progressively less and less available. Sure, without oil we'd lose the current economy, but humanity could survive. Without water? Erm... nope!
Also, as a cold fusion reactor, is it at any risk of producing anything harmful? IE, if it returns water, does it pollute the water returned? Could it, when damaged, emit radiation? People will not have technology in their home that will cause them harm, even if that's via a minor accident. Oil is cheap but how many people do you know store petrol in a house? Most don't: it's a possible fire hazard.
But, assuming it's almost the infinity power generator of it's day and turns trivial amounts of regenerable water into chemicals that can be safely dealt with by a non-expert individual and has zero risk of giving them radiation poisoning via alpha, beta, gamma radiation etc...
It's actually useful
I disagree strongly with my peers on it not being revolutionary for cost, because they are only thinking of houses and people with small incomes who aren't very entrepenurial. As a 'refrigerator sized unit', this would have a huge impact: think vehicles, large boats (which travel by sea), space tech, military and anything else that demands portability.
Maritime industy
Essentially, anything travelling by sea would use this technology. You would revoluntionise the maritime industry because there would be no risk of oil spillages from overturned boats, there would be no need for nuclear reactors (think submarines and aircraft carriers) which have a possible radiation hazard and waste.
Cruises would be able to greatly reduce costs: no more using oil, but endless sea water!
You'll revolutionise cooling systems that use water: because they draw in water to cool down systems. 435
Think along the lines of backup systems.
Search and rescue
You'd change the face of rescue operations: sea operations could go on indefinitely (you can grow plants using special bulbs that demand lots of electricity), and countries with no natural resources or electrical outputs (think Africa) where cost of electricity is prohibitively high, would also benefit greatly. Sure, people say in the first world electricity is cheap, but what options do you have in a ghetto? As a charity you can't just build a nuclear plant - but a refridgeration unit that only takes water? Genius.
Think of those sea-craft that dump tons of water onto forest fires? They would become incredibly efficient because their water load is also their fuel - which means, so long as the pilot isn't fatigued, they can fly for as far as they can carry water!
Water supply
You'd change the face of desalination plants, which take water to be desalinated: not only could they draw power from the water, but they'd be part of the process (it can use sea water to convert sea water into drinking water). This would change agricultural demand overnight as deserts become irrigated by sea-water powered desalination plants.
Environmental
One key issue, though, that it would change (assuming it's non-harmful) is environmental waste. Now, people will try to argue that because they pay less for 'normal' electricity, it's better, but that's a false economy: because the cost comes from the funding of dictatorships via oil purchases, through oil spills in the ocean, through the waste produced by radioactive materials that will take millions of years to become safe and viable.
Overnight, you'd remove the threat of nuclear terrorism (unless your water generator becomes a water bomb...?), but also chemical catastrophes - oil explosions, toxic spillages, overturning vehicles (which deliver the necessary chemicals to neutralise, convert, cool or stop [in the case of a reactor] a runaway system).
Environmental groups would support this. Governments would turn to this. Charities would use it. People who are rich enough to afford this would buy it because it means they aren't at risk from a blackout, or being cut off if the company doesn't get paid, or require a wireless meter along with it's wireless radiation.
Think underground bunkers, where being trapped with a leaking nuke plant is a bad idea or a system that requires oil in a limited supply.
Electric cars
Being able to refill a car with water as fuel is awesome, and anyone who thinks it'd have no use is shortsighted. No longer will your cost of petrol be at a premium! Think aircraft too... 435