The canals within the Gunpowder Mills played a vital role in the manufacture of explosives. 

The Millhead stream drew water from the Old River Lea at the northern extremity of the Mills. This channel, running down the western edge of the site, provided the head of water which was used to drive all the water-powered mills. 

By the nature of a powder factory, it was important that the buildings were spaced well apart to lessen the possibility of chain reaction should a building explode. These canals made transport of the sensitive materials between the process buildings much safer, carried in boats on the smooth surface of a canal, rather than in carts over bumpy roads.  

Even after the arrival of steam driven mills in the mid-nineteenth century, canals were still built as part of the transport system which, by the 1890s, reached it maximum extent of over ten miles. The three levels within the site were linked by locks, two of which still survive. Cast-iron aqueducts were built to carry the canals over the channel of the old River Lew, which meanders through the Mills site. 

One of the powderboats has been restored by the Friends Association and can be found in the Green Hut, about 5 minutes' walk from the main visitor area. These boats carried the process materials around the canal system, always man-hauled by rope from the bank. Horses were never used on site. Perhaps the possibility of a horse bolting with a boat loaded with explosives, gave pause for thought. 

Many of the canals are now dry, although this does not minimise their powerful presence in the landscape. We hope that in time funds can be found to restore them and fill them once more with water.