Asset Condition: Another important factor in determining an asset's probability of failure is the condition of the asset. As the asset's condition deteriorates, it will be more likely to fail. It is important, therefore, to make the best possible attempt to give the assets a reasonable condition assessment. Obviously, assets given a poor or fair condition rating are more likely to fail than those given an excellent or good rating.

The condition assessment should be updated periodically, so that the criticality can also be updated.

Repair History: It is important to monitor repairs resulting from some type of failure and record the type of event that occurred. This information should be as specific as possible to assist the utility in understanding its failure modes. Systems should track when the asset failed (or at least when the failure was discovered), how the failure was determined (customer report, operator observation, lack of service in that part of the utility, etc.), type of failure (e.g., rupture, mechanical failure, small leak), specific location of failure, and any field observations that may help explain the failure (e.g., lack of bedding sand, subsidence of soil, overheating, etc.) Failure history should be tracked on all asset categories.

Past failure is not completely predictive of future failure, but it can provide some indication of the probability of future failure, especially if detailed information on the past failures is collected and reviewed. If the asset failed because its construction or condition was poor, it is likely to fail again unless some action was taken to correct the problem. If the asset failed because of some action or incident unrelated to its condition or operation (e.g., a construction crew ruptured a pipe or a car hit a fire hydrant), it is not likely to fail again after the condition is corrected. If a pipe has failed several times in the past few years, it will be more likely to fail. If the pipe has never failed, it will be less likely to fail in the future.

Operation and Maintenance History: Knowledge of how the asset was operated and maintained will provide information about how likely the asset is to fail. The lack of adequate maintenance is likely to shorten an asset's useful life and cause premature failure.

Historical Knowledge: If the utility has any additional knowledge regarding the asset, it should be considered in the analysis of probability of failure. This type of information may include knowledge of construction or manufacturing practices used at the time the asset was installed or knowledge of materials used in the utility.