I can not find this information anywhere. What is the critical level for a sump pump. In other words, how high can the water level be in the sump pit before it affects the concrete it is sitting against. Should the water be pumped out when it is one inch, two inches etc. below the top of the floor. Example: if I let the water rise to a level of two inches below the basement floor my pump never runs and the water of course does not continue to rise. Is this safe for the concrete or should the water continue to be pumped out below this level?