Thames Water hassaid a couple of wet weeks is not enough to reverse record dry conditions seenin the region in the past two years.
Richard Aylard said most of the rain had gone into the soil, which acted like a "sponge", leaving the Thames region's groundwater and river levels well below normal.
"By the end of March it was so dry that most of the rain we have had since then has just made this sponge wet, rather than getting through to recharge the groundwater we rely on."
"As soon as the weather warms up, the plants will put on a growth spurt and suck up most of the moisture."
Mr Aylard also warned, "It is most unlikely that we will be able to lift the hosepipe ban until we have had some winter rainfall to really recharge the groundwater levels that are still, in places, lower than they were in 1976."