Mark
There are several places that could be leaking
1) make sure it is water and not antifreeze as water is the domestic hot water loop and antifreeze would be the coach heating loop or tank itself
2) the leak could be a as simple a connection a bad pressure relief valve or tempering valve.
Once the front cover is removed you should have access to the above mentioned plumbing and valves but if the water is running out from under the front wall of the unit it is likely the domestic hot water heat transfer loop.
When I bought my coach it s Aquahot had been frozen and the domestic hot water loop had split in almost every loop so I took the unit out of the coach and removed both covers from the unit inside you'll find a round barrel which contains the antifreeze
The domestic hot water loop is simply 160 ft of soft copper 1/2 inch tubing raped around the barrel and then covered with heat transfer cement.
Here is a thread from the past that I commented on about my Aqua hot rebuild
On my unit both the domestic loop and the heating barrel and combustion chamber had holes in them.
Rebuild barrels are available but they are very pricey.
http://beaveramb.org/forum/index.php/topic,10460.msg71162.html#msg71162Hope this helps
Eric