Bristol Water has reported that its reservoir levels have again dropped back by 1% to 51% full on average -this time last year they were 96% full on average.

Bristol Water has attributed the 45% drop to the fact that Mendip rainfall has been persistently -- and, at times, significantly -- below average for month after month after month this year. In December, just 17.7 mm has been recorded (average is 102mm). In November, there was 85.8 mm; the standard average for the whole of November is 94 mm. In October, 75 mm was recorded, 90% of the average. The total for September was just 43.4 mm, 52% of the average expected for the month.

Before August the region saw seven consecutive months of significantly below- average rainfall. In statistical terms, that period remains among the top 5% of all dry periods since 1910 and was the lowest January to July rainfall total since 1976 (the second dry year of a severe two year drought).

The lack of rainfall has affected inflows to the reservoirs and the rate at which they refill -reservoir volumes have actually fallen from the end of November. If the remainder of the year is as dry as the year to date, final outturn volume will be 26,000 million litres, below the drought control curve.

There are only three months left of the recharge period and a net volume of 19000 Ml is required to fully recharge the reservoirs. This will only be possible if each of the remaining three months has average rainfall or above.

To mitigate the impacts, in summer 2010 the company reduced the amount of water taken from the Mendip sources as much as practicable, replacing this with pumped transfers of River Severn water from Sharpness.