Household Dangers for Sewage Systems

It is estimated that between 1% and 5% of domestic waste can be classed as 'hazardous waste' that could, unless dealt with appropriately, cause problems in the water environment.

Phosphate based detergents

Phosphate based detergents in particular are banned in some countries because they add nutrients to the waste stream which can cause eutrophication (or algae growth) in receiving waters.

Chlorine products - bleaches

Chlorine products - bleaches - are another problematic waste stream. It has been said: 'every time you use the toilet you are putting bleach into the environment. It all adds to the chlorine load.'  Most people probably live in the mistaken belief that such products could only have a beneficial effect on the drains, because they kill germs, but this is not the case. With so much organic material and ammonia in sewage, the chlorine products react with these rather than bacteria, which is why chlorine is never added in the early stages of sewage treatment.

The problem is that these chlorine based products react with organic chemicals to produce chlorinated organics - the same group of chemicals as the weedkiller DDT, PCB's and pesticides. They are not biodegradable, they persist in the environment and have a cumulative effect. They are not removed in the sewage treatment process. Many experts predict there will be a general presumption against the use of chlorine products in future, apart from as a residual biocide in the water supply.

Motor oil and cooking oil

People also have a tendency to pour oils of the motor and kitchen varieties down drains. Neither is particularly good for sewage treatment works processes and they sometimes cause problems in the sewers or drains, cooling down to become solid, blocking pipes and creating unpleasant odours.

Garden chemicals

Garden chemicals are another favourite candidate for tipping down drains. The quantities may be small but the number of people doing this means that there are potentially large amounts entering the drains. These, in any quantity, could significantly affect biological sewage treatment processes by killing off the bacteria on which these systems rely.

Sanitary products, baby wipes and cotton buds

Another great bugbear for the drains is sanitary products. These not only contribute significantly to the gross solids entering the sewage system but the plastics used in these items, can when burned, can give rise to chlorinated organics in the combustion gases. Sanitary detritus statistics illustrate the size of the problem - every day, 2.5 million tampons are flushed, along with 1.4 million sanitary towels and 700,000 panty liners.  When disposed of down the drains - along with the ubiquitous cotton buds, baby wipes and the ever more popular cosmetic removing face wipes, cause untold problems. They block pipes and treatment works systems, reduce efficiency in sewage treatment processes and, if released through sewer overflows, remain in the environment to trap and choke wildlife and create a generally unappealing scene.

Medicines and pharmaceuticals

The disposal of unwanted medicines and pharmaceuticals programme has worked well in the past and there have been a number of initiatives for specific waste streams, such as the 'Oil Care' campaign which has set up 1,700 oil banks in the UK to allow motorists to dispose of used oil safely. There has also been a 'Repaint' scheme to recycle partly-used paint cans to community groups, and the British Agrochemical Association has issued guidance for gardeners on use and disposal of chemicals.

The new EEC Waste Directive

Much of our waste policy and guidance is based on European Union (EU) legislation that gives strong direction on waste issues to its member states. The main legal instruments that establish law and policy are called 'directives', and these specify the objectives that the EU seeks to achieve on particular issues.

The directive relates to waste disposal and the protection of the environment from harmful effects caused by the collection, transport, treatment, storage and tipping of waste. In particular it aims to encourage the recovery and use of waste in order to conserve natural resources.

Waste is defined as any substance or object that the holder disposes of or is required to dispose of, pursuant to the provisions of national law.

The range of products that would fall under the umbrella of this directive is extensive -

• mineral and synthetic oils and fats
• paints
• varnishes
• ink
• adhesives and resins
• solvents
• low-pH acids
• high-pH alkalis
• photochemicals
• medicines
• pesticides
• lead and nickel-cadmium batteries and mercury dry cells
• mercury-containing waste, including fluorescent tubes
• aerosols
• equipment containing CFCs
• printed circuit boards and electronic equipment containing internal batteries
• hydrogen peroxide and bleaches
• syringes and needles
• equipment containing PCBs and PCTS
• materials containing asbestos

Remember - with a small sewage treatment system these pollution problems will be made much worse!