The water consumption data and the number of consumers are obtained
by meter readers. Approximately half of all consumers have their meter 
read in a given month. The data for residential water consumption
is the consumption for those residential consumers who had their meter
read in the given month for the last two months. This is considered
a proxy variable for the total residential water consumption.

 Prior to January 1991 the rates for residential water consumption in the
city of London were based on a descending block structure. 
So the more water one used, the cheaper the rate.
For example in 1983, the first 200 cubic feet were  
charged at $3.80 per 100 cubic feet, the next 50000 cubic feet were charged 
at $0.64 per cubic feet; 
and the remainder was charged at $0.53 per cubic feet.
In January of 1991 the billing was changed to encourage conservation.
The new rate is based on an increasing block rate structure.
For example in 1991, the first 1200 cubic 
feet consumed by residential users were charged at $2.011 per 100 cubic feet,
the next 2800 cubic feet were charged at $2.120 per 100 cubic feet, and the 
remainder was charged at $2.228 per 100 cubic feet. 
From June 1993 onwards, 
the environmental tax was added to the bill of water consumption, this tax 
rate charges of $0.254 per 100 cubic feet. 

Original Source: London P.U.C. 

Brief Summary Of The Data Files In The Directory mhsets/londonwq

1.  CONSUM.1
Total consumers 01/83 -04/94                                                   
#missing value for June 1988 (66-th obs.) estimated by                         
#intervention analysis                                                         

2.  PREC.1
Monthly precipitation (millimeter), 01/83 - 04/94                              

3.  TEMPER.1
Monthly temperature (celcius), 01/83 - 04/94                                   

4.  WATERQ.1
Residential water consumption, 1983:1-1994:4                                   
#missing value for June 1988 (66-th obs.) estimated by                         
#intervention analysis