Aizawl, Feb 6 : Mizoram government rolled back the hike in water tariff in the wake of protest from opposition including the Mizo National Front (MNF) and the consumer unions. The state government increased the water tariff with effect from January, but the Public Health Engineering department today issued a press release asking the consumers to approach the department for refund of excess payment for the month. Chief Minister Lal Thanhawla also announced the roll back in the water tariff hike saying that, "unprecedented increase in water bills might be caused by technical defects in the water metres. "Consumers claimed that their water bills shot up to 100 per cent or even 400 per cent, prompting the MNF chief and former chief minister Zoramthanga threatening to launch agitation.