Gary Anderson and Robert Galt with the valve key
One of two Scottish Water employees who fended off a machete attack has told BBC Scotland of the "frightening" assault in Port Glasgow on Friday.
Gary Anderson said it was shocking to be attacked when they were out helping the public on an emergency call-out.
Scottish Water has said it would reconsider how it responded to out-of-hours water supply problems following the incident.
Scottish Water's Paul Maxwell, said it was a "despicable" attack.
Mr Anderson and colleague Robert Galt fended off the two machete-wielding men while working in the town's Southfield Avenue at 2120 BST.
As the attackers hacked into the van door and broke the window with an 18-inch blade, the pair fought them off with a large valve key.
Gary Anderson added: "As I was approaching my van, two youths came up and started using threatening and abusive language.
"When I was stepping into the van, one of them took a swipe at me with the blade and the glass came down on top of me - it was frightening.
"When you're out trying to help the public and this kind of thing happens, it's shocking."
He said his colleague arrived at that point and used the valve to put some distance between the workers and the attackers.
"I don't understand why they did it - I think it was a kind of territorial thing - they were saying 'You're in the Port now'," he said.
"They were throwing half bricks at us as we tried to get into the van and they were attacking it with machetes - the whole incident lasted about 10 or 15 minutes."
Paul Maxwell, Scottish Water's regional manager for Inverclyde, said: "It is unacceptable that our staff should have encountered such an attack as they completed work to maintain water supplies to the town.
"We will now need to consider how best to respond to such out-of-hours interruptions to the water supply in future."
Mr Anderson called for work to be carried in well-known "blackspots" during conventional working hours to protect the safety of staff.
Strathclyde Police said inquiries were ongoing.