Water Quality CE 370 – Lecture 1

Why Is Water Quality Important? Most of the Earth’s water is in the oceans (97 per cent) or locked away as ice. The largest volumes of freshwater are stored underground as groundwater, accounting for about 0.6 per cent of the total. Only a tiny fraction (0.01 per cent) is present as fresh surface water in lakes, streams and rivers. But it is this proportion which is so important for many of our terrestrial ecosystems, including humans.

The Quality of this Fresh Water is Vitally Important, Why? We depend on surface and groundwater sources for our drinking water. We also need water to generate energy, to grow our crops, to harvest fish, to run machinery, to carry wastes, to enhance the landscape. We use water for washing and cleaning, industrial abstraction, recreation, cooking, gardening, as well as simply to enjoy it. Water is also vital as a habitat for both freshwater and marine plants and animals.

What Causes Water Pollution? Many human activities and their by-products have the potential to pollute water. Large and small industrial enterprises, the water industry, the urban infrastructure, agriculture, transport, discharges from abandoned mines, and deliberate or accidental pollution incidents.

How Can Pollutants Enter Water? Pollutants from these and many other activities may enter surface or groundwater directly, may move slowly within the groundwater to emerge eventually in surface water, may run off the land, or may be deposited from the atmosphere.

Pollution Types Pollution may arise as point sources, such as discharges through pipes or may be more dispersed and diffuse Both point source and diffuse water pollution may be intensified by adverse weather conditions.

Diffuse Water Pollution What is diffuse water pollution? Diffuse pollutants The effects of diffuse water pollution Control of diffuse pollution

What Is Diffuse Water Pollution? Diffuse water pollution can arise from many sources. These are generally dispersed and diverse in nature. Individually the sources may be small, but their collective impact can be damaging. Diffuse pollution can be derived from current and past land use in both agricultural and urban environments. It can also include atmospheric deposition. Diffuse water pollution is mainly related to the way we use and manage land and soil. It can affect rivers, lakes, coastal waters and groundwaters. Groundwaters are vulnerable from, and affected by, leaching of pollutants from the land surface and from areas of contaminated land, while surface waters are affected by rainfall that washes over and off the land (run-off). Rivers can also be influenced by the contribution to their flow that comes through springs and seepages from groundwater. Where the groundwater connection with surface waters is high, pollution can pass from one to affect the other. Run-off has increased as agriculture has intensified and as we have built more roads and houses, particularly where we have degraded the natural permeability of the landscape and reduced its capacity to retain water.

Diffuse Pollutants Diffuse pollution results from release of a variety of substances in many different situations. It includes: nutrients such as nitrogen and phosphorus from over-application of fertilizers and manures; faecal and other pathogens from livestock and from overloaded and badly connected drainage systems; soil particles from arable and livestock farming, upland erosion, forestry, urban areas and construction and demolition sites; pesticides, veterinary medicines and biocides from industrial, municipal and agricultural use, poor storage and handling, and run-off; organic wastes (slurries, silage liquor, surplus crops, sewage sludge and industrial wastes) that are poorly stored or disposed of and spread to land; oil and hydrocarbons from car maintenance, disposal of waste oils, spills from storage and handling, road and industrial run-off; chlorinated solvents from industrial areas where the use of solvents is ubiquitous; metals, including iron, acidifying pollutants and chemicals from atmospheric deposition, abandoned mines, industrial processes etc.

The Effects of Diffuse Water Pollution Diffuse water pollution can have significant effects on wildlife and our use of water. These effects include: groundwater and surface water contamination and the subsequent loss, or need for treatment, of drinking water resources; microbiological contamination of water supplies; smothering of fish spawning gravels; nutrient enrichment and eutrophication; oxygen depletion; toxicity to plant and animal life, including endocrine disruption in fish.

Control of Diffuse Pollution Unlike point source pollution, we cannot easily control diffuse pollution by issuing licences or permits. Regulatory approaches have to be more subtle and in many cases need to be well connected to the land use planning system. Diffuse pollution tends to arise from sites not directly regulated by the Environment Agency. However, we can only continue to make water quality improvements by addressing diffuse pollution issues and by adopting innovative ways of controlling the risks from diffuse sources.

Sources of Pollution Help to Reduce River Pollution Most people don’t think the drains beneath their feet can have an impact on their local environment. When we think about river pollution we think of sources like factories, farms and industry. Yet in many cases the pollution in our rivers comes from a much less obvious source – our homes. Incorrect plumbing in the home could mean that waste water from dishwashers, washing machines, sinks, baths and even toilets is flushed directly into your local river. Misconnected pipes are a common cause of pollution to rivers and streams, especially in urban areas.

Sources of Pollution It all starts with drainage In most areas there are two forms of drainage – surface water and foul water. The surface water drain carries rainwater from road surfaces and rooftops into local rivers and streams. Any discharge into this drain flows into the river untreated. This water should be relatively clean and have no negative effect on the watercourse. The foul water drain carries waste water from toilets, sinks, baths and household appliances to the local sewage treatment works. This water is treated prior to being discharged, and again should not negatively effect a watercourse.

How Can Drainage Lead to Pollution? If household appliances are accidentally connected to the surface water drain, instead of the foul water drain, discharges from sinks, toilets and washing machines go straight into watercourses with no prior treatment. When several houses or businesses are misconnected in the same area the damage to a watercourse can be severe. People doing their own plumbing can, accidentally, create these misconnections. Some areas are much more prone to this problem than others.  When water from homes enters the drainage system it flows through sewers before reaching a sewage treatment works, or if the property is misconnected, being discharged straight into a watercourse. The water is discharged through outfall pipes. When a property is misconnected, this effluent from your home will enter the watercourse via an outfall pipe causing pollution. During periods of wet weather, flow rates in the watercourses are high enough to wash away any signs of pollution. However, when the weather is dry, and water levels low, the sewage matter will be more visible.

How Are Watercourses Affected? Sewage effluent in the water causes oxygen levels to drop drastically – in more severe cases the river can no longer support invertebrates or fish.  Oxygen levels will increase again once the pollution has been broken down, diluted sufficiently or removed. Rivers that are severely polluted cannot support any life. And as long as the properties that are misconnected carry on discharging waste water via the surface water sewer, the water quality will not improve.  Within two or three days sewage fungus will grow, covering the bed of the watercourse like a blanket, getting thicker the longer the discharge continues. Sewage fungus will also be thicker if the pollution is more concentrated, such as when flow in streams is lower.  When the discharge stops, the sewage fungus will disappear almost as quickly as it appeared.

Environmental Quality Standards Environment Agencies use a variety of standards and targets to help in taking action to protect and improve water quality. Standards are used to calculate the potential impacts of industry and agriculture and to work out the conditions that must be imposed on discharges in order to protect water quality. They also help in checking national progress in protecting water quality and in working out where action is needed. Standards may have a variety of aims. These include: protecting wildlife and nature; controlling risks to the quality of water abstracted for supply to our homes or used to irrigate crops; making sure that our enjoyment of things like bathing and boating are as safe as possible.

Common Tap Water Contaminants Microbiological Cryptosporidium Total Coliform Bacteria Physical Turbidity (Cloudiness) Chemical Inorganic Contaminants (arsenic, chromium, cyanide, lead, nitrate) Organic Contaminants (Cis-1,2-Dichloroethylene, Atrazine, Dibromochloropropane, Dichloromethane, Pentachlorophenol, Toluene, Vinyl Chloride)

Drinking Water Standards in Saudi Arabia PME Standards

Levels of Standards Organizational City National Regional International

EPA Standards Primary Standards (Health Effects) Microorganisms, Disinfection by-products, Inorganic Chemicals, Organic chemicals, Radionuclides) Secondary Standards (Cosmetic and Aesthetic Effects) Aluminum, Chloride Color Copper Corrosivity Fluoride Iron Manganese