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On the waterfront

Water

During the 20th century, civil engineers contributed much to the development of water and sanitation. However most projects were extensions of the existing infrastructure. Chris Binnie reports.

In 1900, 90% of towns had a municipal-owned water supply. Municipalities were able to take a long term approach and had relatively easy access to financing. Many water supply companies provided water but concentrated on the better off. Inadequate service in London led to eight companies being amalgamated into the Metropolitan Water Board (MWB) in 1904.

However, municipal water and sewerage networks were far from comprehensive. As late as 1913, some 43,000 houses in Birmingham were not connected to the public water supply. It was only in the 1920s that bathrooms began to be built routinely in new middle class homes.

And as late as 1946 in the Metropolitan Water Board area, almost half of homes had only one tap and one water closet.

During most of the first half of the century there was no overall control of water abstraction or co-ordinated long term planning. Each municipality had to promote its own bill in Parliament to obtain abstraction rights.

This meant competition for water resources and some smaller, less powerful, towns were denied their most suitable supply sources. Landowners had unrestricted rights to abstract groundwater even though it drained their neighbour's source. This uneconomic and, at times, chaotic situation continued until the Water Resources Act of 1963 established a formal abstraction licensing system.

At the beginning of the century, there was no water disinfection. Following a typhoid outbreak in Lincoln in 1904, it was found that continuous small doses of chlorine could maintain the bacteriological quality of water at a high standard and this was implemented at many water treatment works.

However, a further outbreak of typhoid at Croydon in 1937 led to 43 deaths. Subsequently, major water undertakers began to disinfect with chlorine routinely.

In 1914, more than 60% of villages had no piped supply, and most relied on nearby wells. The droughts of the 1930s, however, emphasised the poor quality, unreliable nature and inadequacy of such rural supplies, and Government took action. By 1944, the proportion of rural population without a piped supply had fallen to one third.

At the same time, lack of knowledge of how to assess the bacteriological state of water supplies had begun to be appreciated. The result was that, wherever possible, towns obtained their water supplies from upland gathering grounds. To ensure the water was clean, the undertaker would buy the whole catchment, generally removing all habitation and controlling sheep and cattle access.

In the early part of the century, water treatment was by fine gauge wire screens. Water would then be provided by gravity. Some towns did not have sufficient catchments nearby. Birmingham took most of its water from the Elan Valley in Wales, Liverpool from North Wales, and Manchester from the Lake District.

Where lowland rivers had to be used, treatment was by slow sand filtration. This process, however, required large areas of flat land which was seldom available near many of the rapidly expanding towns. It also required expensive steam pumping. Steam pumping continued into the second half of the century. As late as 1952, two thirds of the MWB's pumping was by steam.

Water and sewage treatment standards rose gradually for most of the century, but the infrastructure suffered from neglect as a result of public spending constraints. By 1989, about 15% of sewage treatment works failed their consent standards of effluent quality.

Privatisation in the same year was followed by much increased investment, resulting in only 1% of sewage treatment works failing consent standards in 1998, even though in places these standard had been tightened appreciably.

Because of the strict drinking water standards and the flexibility and innovation that being in the private sector encourages, the last 10 years have seen major advances in water treatment. Several new water treatment processes have become commonplace, for example, ozonation, dissolved air flotation and granular activated carbon. About 99.9% of water samples taken meet the mandatory water quality requirements.

Treatment standards for industrial effluent also progressed steadily through the 20th century. The Victorian era had resulted in much industrial growth, but there were no powers to take trade effluent waste into sewers and there was little technical knowledge of how to treat it. There was no effective controlling legislation. The result was that effluent from factories, slaughterhouses, tanneries, bleach works and other facilities was discharged untreated.

As a result, ecosystems were overwhelmed and the natural processes of river purification could no longer work. Municipal effluent incorporated a large mass of bacteria which absorbed much oxygen. Resulting low oxygen content of the water drove away fish, killed insect life and damaged weed growth.

Most industrial rivers were not just dead, they were deadly. Early in the 20th century, people falling into rivers risked death from poisoning much more than from drowning.

Pollution in rivers had decimated marine life in the 19th century. Major salmon fisheries on the Tyne and Tees were wiped out. However, public concern was muted and there was scant newspaper coverage of these problems. Any suggestion that the law against pollution should be revised was countered by an insistence that legislation would cause irreparable damage to the economy. Thus profit was more important than the environment.

Similarly, coastal towns discharged raw sewage straight into the sea, threatening the holiday trade. A significant proportion of typhoid cases was also traced back to contaminated shellfish.

Smaller towns and villages continued to use cesspits, middens and ashpits for domestic waste. Conversion to water closets and piped disposal was delayed until well into the 20th century when piped water supplies arrived.

Early in the century, there was concern about what the standards of treated effluent should be. A Royal Commission on Sewage Disposal was appointed and in 1912 fixed standards for treated effluent. It was nearly 70 years before discharge standards reflected the required river quality.

At the turn of the century, London County Council chemist Dibden had run pilot trials on biological sewage treatment. In the 1920s the activated sludge process became proven. However, take-up was slow and even in the 1930s more traditional forms of biological treatment were frequently used. A combination of the First World War, a fragmented institutional system with more than 1,000 tiny local authority sewerage undertakers and spending constraints, meant that little money was spent and by the 1930s most sewage treatment works had become semi- derelict.

The activated sludge treatment process was used for the large West Middlesex plant at Mogden in 1935. Activated sludge plants were then built at Beckton and Crossness in east London but were badly damaged during the Second World War and did not become fully operational until the late 1940s.

By the end of the Second World War, the polluting load on rivers had increased appreciably and the rivers had reached their most polluted state.

Postwar repairs to bombed sewers, improvements at sewage works, the closure of polluting industry, the change to biodegradable detergents and the closure of power stations such as Battersea, whose hot water discharges raised river temperatures making them anoxic, all contributed to an improvement.

Full biological treatment was added to Crossness STW in 1964 and to Beckton STW in 1974. At the time, Beckton - treating 800M litres/d - was the largest sewage treatment works in Europe. As a result of these upgrades, the polluting load discharged to the Thames fell dramatically between 1950 and 1980. Indeed, by 1976, more than 100 fish species had returned to the Thames estuary and since 1982 significant salmon runs have occurred every year.

For inland rivers, the 1979 Control of Pollution Act meant that discharge consents could be set with reference to the flow and quality of the receiving water. Many sewage treatment works were enhanced to meet the new criteria.

Since then, the Environment Agency has set River Quality Objectives and even higher standards for sewage treatment.

Historically, coastal towns did little to treat their effluent, mostly discharging it after preliminary screening through short or, in a few places, long sea outfalls. Thus many of the beaches suffered from sewage pollution.

In the early 1990s, the European Union Bathing Waters Directive set tough new standards.

The directive did not lead to the complete eradication of sewage from beaches. As a result, the European Union's Urban Wastewater Directive in the mid-1990s required coastal towns with populations of more than 10,000 to have secondary treatment. The British Government has recently tightened the standard to cover towns with a population of more than 2,000. By 2005, all sewage works will have to meet this criteria.

Chris Binnie is deputy chairman of Binnie, Black & Veatch

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