Heating water on an electric system

[eilthir]

We currently have a standard hot water tank in our airing cupboard, but it uses up a lot of space. We have no other use for the water in the tank other than the kitchen sink, bathroom sink and the (very) occasional bath, as we have an electric shower and cable-mat underfloor heating. It is an enormous waste of energy to heat the big tank for a few liters of water.
Is there a product on the market (for an electricity only system) that we could use to replace the large tank, that would give us hot water on demand?

Thanks,

Kimberley