We have just recently installed a new roof on a semi-detached property where a bonding gutter was needed between both houses. The client was very sceptical of this until we fully explained just how they worked.
Below is a typical photo of just how they operate keeping rainwater at bay. You will see the raised profile of the bonding gutter preventing any water ingress and just simply sends all the rainwater into the guttering at eaves level.
All the leaf's are brown and the sky's are grey!
Do you live near a tree?
If the answer is yes they will be a good chance that some leaf's will have been blown into your gutters and drain pipes and with the amount of rain we have had recently this could cause future damp problems.
Your Gutters and drain pipes can be cleaned very easily, quickly and more importantly very cheaply. Put your mind at rest if your unsure if you need your gutters cleaning.