I am using the Johnson Geyser in my toilet for last 5 years. The inner container was replaced after one and half year of purchase - and now it is again leaking.They said the guarantee for the inner container is for 10 years - but they claim they will not change more than once free of cost! The company and the product are equally bad.
So consider buying that product only if you have money to waste. The cost of the geyser is also not great, a 35 litre one costed 5K+ in 2005, which is as good as geyser from any other company.