One in five Irish home-owners is now under water.

The Bank of Ireland alone says that 40,000 of its 199,000 residential mortgages (20 per cent) are under water.

The bank holds 25 per cent of the Irish mortgage market which means that an estimated 160,000 home-owners in Ireland are in negative equity.

These numbers are in line with a report from the ESRI (Economic and Social Research Institute) which says that 200,000 Irish home owners will be under water by the end of this year.

And there's no let-up in sight

David Duffy of the ESRI says first-time buyers will be under water for the first 10 years of their mortgage.

Which begs the question; Why buy when rents are so cheap?

Duffy says that the average amount tied up in negative equity is about €50,000 while people who borrowed in excess of 92 percent of the purchase price owe $54,000.

That might be true but I know of several people who are down much more than that on apartment purchases.

One man who was offered a new job overseas is now paying a $1,870 mortgage on an apartment which he can only rent out for $750.

He paid $307,000 for it in 2007 and he could buy one today for $227,000.

It looks to this inexperienced economist that the one-in-five number will rise soon and the average amount of negative equity will rise even more sharply.

Check out for more figures.