Standard warranties are intended by the membrane manufacturers to cover defects in materials and workmanship associated with the membranes. A more stringent custom membrane warranty is often closer to an insurance policy on the performance of the entire plant rather than just the membranes. In most cases, the membrane manufacturer has little control over the components and operations that can cause the problems with the membranes covered by custom performance warranties. These types of custom warranties, or insurance policies, are most appropriately provided by the RO plant operation and maintenance parties rather than the membranes manufacturers or original equipment manufacturers.