Bottled Water vs Water Filter: The 6 Year Cost in Ireland

One person buying a bottle of water a day in Ireland spends about €547.50 a year, according to Refill Ireland. That is €3,285 over six years. An ArkkZ reverse osmosis system costs €439 today, with filters fitted. Filter changes over the next six years come to about €737. Total: around €1,176. The difference is over €2,100, and that is before you count the shopping trips, the storage space and the recycling.

I did this sum on the back of a shopping receipt one Tuesday evening, and I have not really stopped thinking about it since.

Why does bottled water never feel expensive?

Here is the thing about buying bottled water. It never feels like a real expense. It is €1.50 here, a multipack there, a few bottles thrown in the trolley because the kids are going to camp and you want something in their bags. No single purchase is worth thinking about twice.

Refill Ireland, the campaign group behind the national Tap Map, puts the figure plainly:

Irish people spend over €100 million a year on single use plastic water bottles, and refilling every day would save an individual €547.50 a year. That works out at a bottle a day at typical Irish shop prices.

Now think about your own house. If you have two adults doing the same thing, you are looking at over €1,000 a year leaving the household for water. Add teenagers who buy bottles at school or at the shop on the way home from training, and the number climbs again. And unlike a broadband bill or a bin charge, nobody ever sits down and reviews it.

That is why I wanted to lay this out properly, over a full six years, with every cost included.

How much does bottled water cost in Ireland each year?

Let us use the Refill Ireland figure of €547.50 per person per year. It is a conservative starting point, because it assumes one bottle a day and nothing more.

Here is how it accumulates:

Year	Cumulative bottled water spend
Year 1	€547.50
Year 2	€1,095.00
Year 3	€1,642.50
Year 4	€2,190.00
Year 5	€2,737.50
Year 6	€3,285.00

Three thousand, two hundred and eighty five euro. For one person. For water.

And you have nothing to show for it at the end. No asset, no appliance, no improvement to your home. Just six years of plastic that has already gone into a bin.

What does a reverse osmosis system cost to buy and run?

This is where people get nervous, and fairly so. A filtration system has an upfront price, and that price feels much more real than €1.50 at the till. So let us be exact about it.

The ArkkZ reverse osmosis system from Renewell Water has a recommended price of €595. At the time of writing it is listed at €439, and installation across Ireland and Northern Ireland is included in that price. There is no separate plumber to pay.

The system arrives with its filters already fitted, so year one costs you nothing more. After that, filters are the only ongoing cost.

There are two of them, and they run on different clocks. The main cartridge is swapped every twelve months. The membrane lasts much longer, usually two years or more.

So a normal year costs around €99 for the cartridge on its own. A membrane year costs around €220 for the cartridge and membrane together. You change them yourself. It genuinely takes about a minute.

Your first change falls twelve months after fitting. Across six years of ownership that is five changes in total, and the filter bill comes to roughly €737.

Bottled water vs Arkkz Reverse Osmosis: the 6 year comparison

Here is the whole picture side by side. The reverse osmosis column uses the current €439 price, with no filter spend in year one because the system comes with them fitted.

Year	Bottled water (one person)	ArkkZ, running total
Year 1	€547.50	€439
Year 2	€1,095.00	€538
Year 3	€1,642.50	€758
Year 4	€2,190.00	€857
Year 5	€2,737.50	€1,077
Year 6	€3,285.00	€1,176

Six year saving: around €2,109.

If you buy at the full €595 price rather than the current offer, the six year total comes to €1,332 and the saving is still around €1,953.

Two things stand out to me in that table.

The first is that the system is cheaper than bottled water in year one. Not year three, not year five. The very first year, and by more than €100.

The second is the shape of the two columns. The bottled water column rises by the same amount every year, forever, and it never stops. The ArkkZ column has one big step at the start and then flattens out into a small annual cost. Those are two very different money stories. The gap between them gets wider every year you own the system.

And remember, the bottled water column is for one person. The ArkkZ serves the whole house, unlimited, straight from a tap on your worktop.

"Most families do not realise they have already paid for a filtration system several times over. They just paid for it in small amounts, at the checkout, over years."

Simon Newell, Founder and CEO, Renewell Water

What are the hidden costs of bottled water?

The money is only part of it. When I actually thought about what buying bottled water demands from a household, the list was longer than I expected.

Your time. Water is the heaviest thing in the trolley and the most annoying thing to run out of. If you are making a special trip to the shop even once a fortnight because you are low, that is roughly twenty six trips a year. Call it twenty minutes each with parking and queueing, and you have spent the guts of nine hours a year buying water.

Carrying it. A twelve pack of two litre bottles weighs about twenty four kilos. Out of the trolley, into the boot, out of the boot, into the kitchen. Anyone with a bad back or a flight of stairs knows exactly what I am talking about.

Storage. Bottled water takes up a corner of the utility room, the bottom of the pantry or a slice of the garage. That is space in your home that you are paying a mortgage or rent on, permanently occupied by water you already own.

The recycling. This is the one that gets me. Ireland recycles just 34 percent of its plastic packaging. Two out of every three bottles are never recycled at all. 1.4 million single use plastic water bottles are used every week in Ireland. So on top of the money and the effort, most of what you carry home ends up somewhere none of us want it. A Coastwatch Ireland survey in 2021 found 3.9 plastic bottles on every 100 metres of our coastline.

None of these appear on a receipt. All of them are real.

Does bottled water contain microplastics?

There is one more hidden cost worth knowing about, and it is the one that changed how I look at a bottle of water.

In January 2024, a team at Columbia and Rutgers published a study in a leading science journal. They used a new laser method to count plastic bits in bottled water. These bits were far too small for older studies to spot. On average, they found around 240,000 plastic bits in a single litre. That is 10 to 100 times more than earlier counts. About 90 percent of them were nanoplastics, meaning bits smaller than one micron.

Some of it seems to come from the bottle itself, which sheds tiny flecks when you squeeze it or leave it in the heat. Some of it seems to come from the cap, each time you twist it open.

Scientists are still working out what this means for human health, and I am a home columnist rather than a doctor, so I will not go further than the researchers do. But it is a genuinely strange thought that the premium product might be carrying something the alternative does not.

Is it cheaper to filter your own water?

If you buy bottled water regularly, the arithmetic is not really close. You are spending over €500 a year, per person, on something that arrives at your house in packaging you then have to store, carry and dispose of.

A reverse osmosis system turns that into one purchase plus a small yearly filter cost. Everyone in the house gets as much filtered water as they want.

The ArkkZ Water Filtration System is the one we fit in most Irish homes for exactly this reason. Fitting is included, and you swap the filters yourself in about a minute. Renewell Water is Ireland's Number 1 rated water filtration company. If you want to know what real customers think, the reviews speak for themselves. You can read them at renewellwater.com/reviews.

Do the sum on your own household. I think you will be surprised by what you find.

Sources: https://refill.ie/the-problem/, access in Septemer 2026.

https://www.publichealth.columbia.edu/news/bottled-water-can-contain-hundreds-thousands-nanoplastics , acess in September 2026.