UK consumers are buying processed meats regularly pumped-up with up to 30% water, the Food Commission has said.
Some sausages were found to contain only 37% meat
The organisation is calling for clearer labelling of products, showing the specific quantity of added water - not currently a legal requirement.
A survey in its Food Magazine found added water in bacon, ham, chicken, lamb, turkey, sausages and hot dogs.
The Food and Drink Federation said adding water was legal and could be "an essential part" of production.
In a statement it said: "Added water can be an essential part of the production process and can be necessary to retain flavours and succulence to ensure that the product is acceptable to consumers."
But the Food Commission said food or drink was often sold by weight or volume.
It said that allowed "unscrupulous" manufacturers to "bulk out products with water and other cheap ingredients, before selling the produce on at full price".
Companies can legally add up to 5% water to any food without declaring it as an ingredient.
If they add more than that - or over 10% for bacon or gammon - it must be stated on the label.
But Food Commission spokesman Ian Tokelove said the specific proportion of added water did not have to be stated.
Sainsbury's Gammon Plate Steak 76%
Asda's bacon rounds 78%
Thomas Shaped Ham Slices 78%
Bernard Matthews American Fried Chicken 62%
Turkey Twizzlers 34%
Dairylea Lunchables turkey 58%
Asda Smart Price Chicken Roll 58%
The water is added by soaking, tumbling or injection, and can be held in place by phosphate additives or ingredients like starch or gelatine.
Mr Tokelove said many shoppers were unaware that processed meats could contain between 10 and 30% added water.
He called for clearer labelling "with a declaration on the front of the packet showing the percentage of added water."
"The information given on the labels is inconsistent, sometimes hard to find, and often very confusing."
"The water won't harm you, but do you really want to spend your hard-earned cash on watered-down ham and soggy sausages?"
Companies are required to declare the percentage of meat in a meat product.