Scottish Water have therefore launched a campaign to stop people flushing rubbish down their drains and clogging the sewer system - which costs £7 million a year to taxpayers.
Around 80% of the 40,000 blockages last year were caused by people putting the wrong things down sinks and toilets - from nappies to cooking fat, and even pants and jeans.
False teeth was also a popular item for people to drop down the drains in a list of things you really shouldn't flush into the sewer.
The utility company is running a broadcast campaign to help people understand how they can play a part in keeping the system flowing while saving on household bills.
"Cooking fat, oils and grease coupled with bathroom waste such as cotton buds, nappies and baby wipes creates a perfect storm of solidified fat and material that can't break down easily like toilet paper and collects in large clumps beneath Scotland's streets," Scottish Water says.
"This leads to the misery of flooding of thousands of properties across Scotland, leaving householders and communities with the hassle and expense of repairing damaged property and sometimes resulting in pollution to local rivers and burns.
"In addition, sometimes Scottish Water's sewage workers sometimes have a good yarn to tell. A woman in Kippen called the sewage works to say her husband had been sick and lost his false teeth down the loo. When the boss explained he gets about six sets of these a month, she asked if her husband could come down and try some out to see if his had come through."
Drains are designed to take only used water, human waste and toilet paper, the firm insists.
Iain Gulland, director of Zero Waste Scotland, said: "I welcome the launch of this new initiative by Scottish Water to raise awareness of how to keep the sewer system clear of waste.
"Where food waste is concerned, it's important that consumers understand how to dispose of it properly. Food waste that cannot be used or avoided is easily recycled or composted. Over half of households across the country now have access to food recycling services and we are continuing to roll these out in towns and cities nationwide.
"Waste is a resource and there are significant environmental and economic benefits for Scotland if we work together to manage it more efficiently."
Top 40 list
1) An outboard motor for a boat
2) A fully functioning clothes iron
3) A scaffolding pole
4) A football
5) Toy soldiers (used to be mounted on the wall at the waste water treatment works in Dumfries)
7) 2x4 timber
8) A dead sheep
9) A mattress
10) Hand truck /parcel trolley
11) False teeth
12) Golf balls
15) Credit card that belonged to one of the guys who work for Scottish Water - was stolen in the pub and flushed down the pub toilet - put his wallet in his missus' handbag, was stolen, flushed and then it turned up in the screens at the sewage works
16) Mobile phones
17) A frog was found inside the pump right next to the propeller - how he got in there is a mystery
18) A live badger was found in a pumping station well at Drongan
19) Traffic cone - Moodiesburn
20) Timber - Moodiesburn
21) A dead, fully grown, cow, found in the storm tanks at Gatehead. Turns out a cover had been removed from a manhole in a field and the cow had fallen in. Thanks to the tag on the cow's ear the farmer was traced
22) A pair of trousers recently turned up at Kirkcaldy waste water treatment works (WWTW)
23) A live otter from the aeration ditch at Dornoch WWTW
24) A live salmon at Seafield WWTW
25) A tractor tyre
26) An Action Man figure, who still had his boots on
27) An orange
28) A railway sleeper
29) A giant Winnie the Pooh cuddly toy found in East Kilbride
30) A fax machine was found in East Kilbride
31) A pink bicycle was found in East Kilbride
32) A huge amount of straw in Tranent, East Lothian which possibly came from a farm and had blocked the sewer
33) A giant bucket full of potatoes
34) A huge amount of turnips
35) Carrots turned up in a manhole in a field
36) A white patio chair in a sewer at Goosedubs Lane, Glasgow
37) A golf club caused havoc in a sewer in Ayr
38) Enough apples to fill a pail turned up in a sewer trap in Buchan
39) A whole load of cooked potatoes somehow got into the network and were found in a manhole in Thurso.
40) Stones of all shapes and sizes turn up all the time.