Asked by Ceridwen and Reg George, Essex
Dear Richard,
A great many river cruises are now on offer from several tour operators. We went on an Elbe cruise last year and although the itinerary had to be altered because the Elbe was in flood it was still a very comfortable way to have a holiday and see interesting places. We are both very elderly! Are River cruises environmently friendly? What happens to the sewage for example? What do you think?

Even in the height of the industrial revolution there weren’t as many boats on Britain’s waterways as there are today. Some 29,000 licensed boats now cruise up and down Britain’s rivers and canals, and thousands more operate throughout the continent. Carbon-wise, river cruising is one of the greenest ways to travel, but it can cause pollution and disturb wildlife. There are two key laws that apply universally: it is illegal to discharge toilet waste and flush more than 5mg per litre of oil or fuel into the water…

The Royal Yachting Association and British Marine Federation provide a list of places in the UK that provide “pump out” facilities where you can dispose of toilet waste along the river or canal (thegreenblue.org.uk).

It’s also far greener to go on an electric boat rather than one that uses a diesel engine; they are cheaper to run (most marinas now have charging facilities), their stealth makes it easier to get closer to wildlife, and their low wash won’t disturb bird nests on the river banks. The website of the Electric Boat Association (electric-boat-association.org.uk) provides a list of companies that run electric river cruises, such as Avon Boating in Stratford (avon-boating.co.uk), and the Phoenix Fleet on the Norfolk Broads (phoenixfleet.com). Better still to go on a solar-powered boat, such as the 46ft Solar Heritage catamaran in Chichester harbour (conservancy.co.uk) and two 40ft launches on Lake Coniston in the Lake District (conferry.co.uk).

This article, by Richard Hammond, was first published in the Guardian.