VII. A MATTER OF ECONOMICS
The story of sewerage in Leeds is inevitable intertwined with that of the wider social and economic developments. The rate of progress with public and estate sewer construction in the city was dependent on many external factors, as can be seen from the graph below.
Sewer construction work formed the basis of some unemployment relief schemes (in the Hawksworth Valley for example) during the depressed years of the early 1920s. The widespread industrial struggles of the 1920's too had their reflection amongst the Sewerage Engineer's employees at Knostrop.
The 1921/22 Annual Report of the Sewerage Committee recorded that "from 2/4/21 to 7/7/21 (both days inclusive) all treatment was suspended in consequence of a general strike of workmen." Amazingly, the Council's General Purposes Committee report for the same year noted that "During the period under review no cases of withdrawal of labour were reported of any of the workpeople employed in Corporation Departments." ! Can it really have escaped this Committee's notice that all the city's sewage had been flowing totally untreated into the river for 1/5 of the year?
Notwithstanding lapses such as this, the sewerage system had become an indispensible part of the economic infrastructure. Industrial use accounted for a significant portion of the dry weather flow taken for treatment. By 1938, out of a total dry weather flow of 19.42 million gallons per day going for treatment, 5.35 million gallons was attributable to industry. The make up of this volume is shown in Table 2:
| Type of Industry or Trade | Gallons/Day |
| Tanners, Curriers, Fellmongers | 486,000 |
| Piece & Wool scouring/dyeing | 2,749,500 |
| Chemical Manufacturers | 86,800 |
| Oil, Soap, Tallow & Candles | 94,900 |
| Breweries & Vinegar Manufacturers | 729,400 |
| Slaughter Houses & Casing | 75,500 |
| Garages | 50,400 |
| Laundries | 533,500 |
| Unclassified Trades | 546,800 |
| TOTAL | 5,352,800 |
Table 2. Industrial Effluents to the Sewers (1938)
Neighbouring Bradford was more fortunate than Leeds in the industrial composition of its sewage. During World War I Bradford's Esholt Treatment Works actually ran at a profit on the basis of selling the clear grease (removed from the sewage "by the joint agencies of steam and pressure") which emanated from dirty wool, cleaned with tons of soap.