Resource 10

The humble toilet ¹

The first modern water closet with a cistern and flushing system was designed by Sir John Harrington in 1596 and used by Queen Elizabeth I. Sir John had also written a book about his invention. The book was attached to the wall of the toilet so the Queen could have a read while sitting on her other throne.

It took until the late 1800s to perfect the flush dunny. In a test, George Jenning's pedestal vase managed to flush away ten apples, one sponge, four pieces of paper and plumbers smudge coated round the bowl.

Although Thomas Crapper is often thought of as the inventor of the flush toilet, what he actually invented was the 'valveless water waste preventer', the flush mechanism we still use today. In fact, dunny design has not changed much at all in the past 100 years.

How does it work?

The modern flush toilet has two parts - a cistern and a bowl. Together they form a flush and siphon system. When you press the button or pull the lever, water from the cistern swirls round the bowl, flushing away all the waste. The waste and most of the water is siphoned off down the waste pipe except for the last of the water, which remains behind in the S-bend or trap. This is to prevent any unpleasant gases from getting back into the toilet from the sewer pipe. After the cistern empties, the flush valve shuts off and the cistern fills up again. A float which rises with the water is connected to the flush valve and eventually closes it off, stopping the cistern from overflowing.

See if you can label and explain the various parts of the toilet on the diagram below.

Parts of the modern toilet
Parts of the modern toilet.

To find out more about toilets, visit the most interesting 'Toiletology' site: www.toiletology.com

¹ Based on an activity from: Keith McTaggart and Paul Saddler 1993, Flushing Dunnies, Melbourne Water and Science Teachers Association of Victoria.