Now Ryanair wants to charge you a pound to spend a penny

Go before you go: that is the message from the bog-standard budget airline, Ryanair. Michael O'Leary, the carrier's controversial chief executive, has incensed consumer groups by proposing a £1 charge for the last free on-board "frill": the lavatory.

Mr O'Leary leaked the plan to breakfast news yesterday, warning that "people might have to spend a pound to spend a penny in future", with the airline planning to fit "a coin-slot on the toilet door".

Opponents queued up to pooh-pooh the wheeze. Rochelle Turner of Which? Holiday said: "It seems Ryanair is prepared to plumb any depth to make a fast buck." Frances Tuke, of Abta, the Travel Association, said: "This is in the realms of 'You couldn't make it up.' We think it's outrageous. It's underhand to charge for something which should be part of the deal."

A spokesman for Ryanair, Stephen McNamara, had apparently not been privy to the new policy. He issued a statement saying: "Michael makes a lot of this stuff up as he goes along and while this has been discussed internally there are no immediate plans to introduce it." He added, though: "Not everyone uses the toilet on board one of our flights but those that do could help to reduce airfares for all passengers."

While Ryanair is flush with cash and, therefore, better placed than many airlines, it has been hit by the free-falling pound. As an Irish company many of its costs are in euros, while fuel and aircraft leasing costs are in US dollars. But its main base is the UK, with earnings in sterling – these days worth little more than toilet paper.

In addition, inopportune hedging has seen the airline paying well above the spot rate for aviation fuel. So the carrier is seeking every opportunity to boost "ancillary" revenues. Last week, the airline announced plans to axe check-in desks, forcing every passenger to check in online. A move to charge for using the on-board lavatories is the logical conclusion of the no-frills revolution that began in Britain in 1995. That was the year a young entrepreneur, Stelios Haji-Ioannou, launched easyJet. He redefined air travel by abolishing travel agency commission, minimum-stay restrictions and complimentary in-flight catering.

Ryanair has since taken the lead as the most hardcore of the no-frills carriers, charging £9.50 for using a check-in desk and the same for a suitcase checked into the bowels of the aircraft.

Several problems will need to be addressed before a charge is introduced. A coin-in-the-slot mechanism that accepts, say, £1 and €1 coins would be of little use to Swiss and Swedish passengers aboard a flight from Basel to Stockholm, both outside the euro area. Some female passengers will feel aggrieved at having to pay to deal with the onset of a period while on a Ryanair flight.

Parents who decide to change their baby's nappy in the cabin rather than in a washroom could anger other passengers. And charging for toilets is likely to dampen demand for inflight drinks. But Mr O'Leary rejected a suggestion that some passengers may be too poor to pee: "I don't think anybody in history has got on board a Ryanair flight with less than a pound."

Other airlines, such British Airways, dismissed Ryanair's latest plan as potty. "We've got no plans to do that," said a spokesman for BA. Andrew McConnell, of easyJet, said the idea did not hold water: "Inflation appears to have gone crazy if it now costs £1 to spend a penny."

Groups representing the elderly and the incontinent also attacked the plan.

Strangely, the loos ruse was presaged in a post on the website ihateryanair.co.uk, in which an anonymous traveller wrote: "So Mr O'Leary, in your bid to charge us for every sodding thing you can, how long will it be before you charge your passengers to go to the toilet?"

Ryanair rules: How you can fight back

Pay for your flights with a Visa Electron card – otherwise you can add £9.50 to every return flight for paying with a debit card. If your bank does not issue Electron cards, you can pay with someone else's card (with their permission).

*Check all details before you click "buy"; entering a wrong name (eg, "Bob" when the passport says "Robert", or a woman's married name when the passport bears the maiden name), can cost up to £145 to change on each flight.

*Be aware that carrying more than one piece of cabin baggage – even duty-free purchases – could result in you being sent back to check-in to pay a £30 "fine".

Don't pay the extra fee for "priority boarding". On the average Ryanair flight there are 36 empty seats.

*Know your rights when things go wrong. If a flight is cancelled and it is not the airline's fault you have few rights under EU legislation – the airline only has to give you your money back. But if a short flight is delayed, not cancelled, then, after two hours, the airline has to offer refreshments and phone calls, regardless of the cause of the delay.

*Take an empty bottle through security and fill it at the water fountain "airside" to avoid the £3 onboard water; in extremis a container could save a toilet trip.