Oil on the water! Sneak a peek at your leaky bilge

Did you know?

Every hour enough plastic to fill two bin bags is washed into our oceans from canals and rivers.

The Sun is shining, the birds are singing, a day to savour on Britain’s canal network. I know I’m asking a lot as we are still deep in winter, but let’s picture such a setting. You are alone at last to enjoy this oasis of calm when you are confronted by a plume of oil upon your arrival.

I think we can all agree that oily water does not spring to mind when imagining our own waterway paradise and nor should it. A large proportion of the oil we see on the water is preventable and results from boats discharging their bilge water not knowing that it contains oily contaminants.

Each year the Canal & River Trust (and on occasions, the Environment Agency) receive a barrage of calls from people spotting oil on the waterways to which we must respond.  Responding to these easily avoidable incidents consumes resources which could be allocated elsewhere to improving and enhancing our waterways.

Often, the visible oil resulting from oily bilge water is spread so thinly on the surface of the water, that oil absorbent spill pads do not work and very little can be done to prevent any resulting harm.

What’s the problem?

Most boats will collect bilge water in their lifetime and it can often contain oily contaminants. Although only a small quantity of oil usually finds its way into bilge water, the impact is still problematic and impacts boaters, anglers, walkers, wildlife and cyclists. Most immediately, oil pollution like this reduces the amenity value of the waterway as it is odorous and unattractive.

Water quality is also reduced, contaminated by a range of compounds including oil, grease, lubricants, hydraulic oil and even anti-freeze. Carelessly pumping out oily water can also increase dredging disposal costs due to contamination of the sediment, often resulting in reduced dredging due to the increased cost. The knock-on effects on wildlife are varied; oils can smother life and have impacts on the food chain, whilst more toxic compounds found can kill some animals and plants even at small concentrations BUT this is all preventable.

Although bilges can be kept relatively dry with good housekeeping, some water accumulation is inevitable. A boat will cease to be a boat for much longer if water is left to build up inside for too long.  So how best do we remove bilge water whilst ensuring it does not contain any of these undesirable pollutants?  

How can I help?

Pumping clean water from your bilge to the canal is perfectly legitimate on the condition that it is actually clean. It is internationally recognised that oil in discharged bilge water should never exceed 15ppm (parts per million). To give this figure perspective, one drop of oil in a litre of water equates to 40ppm. A little oil goes a long way!

Oil usually enters bilge water through engines leaking oil, via stern glands and water washed in from other areas of the boat. We’ve put together a few pointers below on how to prevent this from happening.

  • Well maintained engines shouldn’t leak oil. Check the drip trays underneath, if they keep getting oily, find and mend the leak. If any engine oil is spilt, mop it up using absorbent pads (or a nappy). You can often buy absorbent pads from chandleries, boatyards or marinas;
  • Place absorbent pads under the engine and gear box; monitor these and pump out regularly into a drum. The oil can be taken to a local boatyard to be recycled;
  • Greasing the stern gland can prevent the ingress of water whilst the boat is stationary;
  • Securing the weed hatch and replacing it if necessary can prevent water entering the engine bilge;
  • Tightening all plumbing by keeping the nuts compressed and watertight will reduce leaks. A dry bilge cannot discharge oily water;
  • Use a bilge sock to absorb oil and fuel in the bilge;
  • Using water based lubricants and biodegradable fuels will help to reduce the pollution impact if an incident does occur;
  • Fit a filtration system to your bilge pump to easily remove oil from the water; Cartridges can be replaced cheaply. Alternatively, ensure the pump is cleaned regularly with non-phosphate based cleaners;
  • If you do have oily bilge water, invest in a cheap hand pump and discharge directly into drums; your nearest boat yard will then ensure its safe disposal.

Last date edited: 30 January 2015

About this blog

The environment team

The Canal & River Trust has top team of committed experts and enthusiasts, who help to protect our waterway environment and improve it for both people and nature. Follow this blog to find out more about the hugely varied work they carry out.

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