Problems Caused By Biofilm

Energy Costs

Biofilm is 85-95% water. It acts as an insulating layer of stagnant water. As water has one fifth the thermal conductivity of carbonate scale, a 1 mm biofilm is has the equivalent insulating properties of 5 mm of scale, resulting in greatly reduced heat transfer efficiencies at heat exchange surfaces.

Biofilm Can Cause Corrosion

Anaerobic (live without oxygen) sulphate reducing bacteria can form and live in biofilm. These produce sulphuric acid which will corrode pipes and can result in leaks.
Aerobic (need oxygen to live) iron-oxidising bacteria can cause serious corrosion to pipes.

Biofilm Increase Frictional Drag

As biofilm grow in pipes, they reduce pipe diameter resulting in frictional drag, pressure drops, and increased pumping power.
A 1.5 mm biofilm reduces flow area by 42%. This results in reduced efficiency and increased costs.