They added that people who had been sick were on the road to recovery but the water still wasn't.
"Together we can send a strong message that the water we drink, swim in and use to grow food needs to be clean and pure again," Mr Barber said.
"We need to work together and rebuild our region's reputation and protect our water now and for our future generations," Mr Harvey said.
There has so far been a focus on Havelock North, but Hastings businesses and homes had been impacted, too, after being given chlorinated water.
"Many say this is a one-off incident, but we need to make sure that this never happens again and that we can drink from our taps in full confidence that it's fresh, clean, un-chlorinated water," Mr Harvey said.
Ngā Marae o Heretaunga and Ngati Kahungunu Iwi are endorsing the walk.
Both men urge school sport teams to get involved with winter sport competitions taking a huge hit with cancellations during the crisis.
"Wear your team uniforms and finish the season on a positive note," they said.
A traffic management plan will be put in place and there will be pure water stations.
There will be free transport back to Havelock North after the walk.
- People are asked to gather at 8am at the Havelock North water fountain. The 4.5km walk begins at 8.30am.
