In natural gas industry, measurement of process variables allows to assess the quantity and quality of commercialized gas. Nevertheless, since errors, gross and random are always present in measurements, mass and energy balances are not satisfied. This situation leads natural gas distribution companies into invoicing issues. In this paper, a computational tool is proposed, which guarantees that the law of conservation of mass is obeyed by decreasing random error effects and detecting systematic deviations in the measurement equipment (gross errors). This tool is based on Data Reconciliation (DR) and Gross Error Detection (GED) techniques. Different DR and GED methodologies were studied by means of assessment of their advantages and disadvantages. Non-conventional DR and GED methods are proposed as part of the developed tool in order to obtain accurate reconciled results in cases of difficult gross error detections on natural gas distribution systems. The tool was validated by a typical literature problem, and it was then applied to a natural gas distribution network. Results were in agreement with reports of failures of some instruments.