No problem if there is room to fit another cable in.
If not, you can fit another earthblock or bond the gas and water of one length of earth cable without cutting the cable. To do this:
cut the sheath of the green/yellow earth cable about 12″ down, so that there is a pigtail long enaugh to connect back into the earthblock.
Bend the bare cable (where you have removed the sheath around the bonding strap terminal ~(use a screwdriver to bend the cable round to get the shape)
The earth cable then carries onto the water mains, thus its one length of cable and not cut between gas and water.
I would work in reverse from the water main when connecting.
Hope this makes sense!
