Some mistakes related when writing data to EPANET is written below. All this may result on running error message “system ill-conditioned”.
a) junction without valve: It is very usual to simplify analysis consider the end of a pipe of fixed flow, but if this is an end of network this become a difficult of processing if this is not associated to a valve, so the solution to solve this problem is add a valve that satisfies the flow conditions at considered point.
b) reservoir with incomplete data: This EPANET element may corresponds to a lake, river, dams. Completing description on the way of connecting them to the network solves the problem.
c) pipe without roughness or another missing value: To solve this problem you will need to use your calculator or calculate on a sheet computer
d) inconsistent geometric data: at this topic are levels higher then tanks top level, lower point of a pipe with disagreement of lower point of next structures. An review of levels solve the problem.
e) pressure that makes no flows. This happens when a default value is used instead of the correct value. A review of pressures using Bernoulli equation probably solves the problem.
