1. We will pay for loss or damage to covered property caused by water that backs up from a sewer or drain, subject to the following limitations:

We will not pay for loss or damage under this Additional Coverage caused by the emanation of water from a sewer or drain that itself is caused by, or is the result of "Flood," surface water, waves, tides, tidal waves, overflow of any body of water, or their spray, all whether driven by wind or not;

A denial was issued as follows:

In view of the cited exclusions, the water damage to the basement is the result of flood and ground water, therefore we would not make a payment for this loss.

The loss was not caused by flood or surface water but a high water table that overwhelmed the pumps capability to function due to two major rain events one year ago. When the water table receded, the pump functioned so it was not failure in the sense one thinks of failure i.e., mechanical or electrical. Water entered through the sump, through some cracks in the floor. 

My belief is that this is a covered loss. I could not find any information on the definition of "sump pump," the purpose of a sump pump, or the definition of "groundwater."

The carrier used the term "groundwater" in the denial. That is not addressed in the endorsement.

Connecticut Subscriber

 It does not sound like the water backed up through the sump pump but came through the cracks in the floor. This type of loss would be subject to the part of the water exclusion that states, "Water under the ground surface pressing on, or flowing through…floors…basements." (This can be seen in the ISO BP 00 03 01 10, B.1.g.) If the insured has purchased sewer and drain backup coverage, it would not apply to this type of loss. However, if it can be shown that the water really did overflow or was discharged from the sump (as opposed to seeping in through floor cracks), that would be covered.