Indah Water Konsortium is Indah Water.
You really never heard of IWK? It's the national sewerage company, they handle all the sewage waste.
Website: http://www.iwk.com.my/

The bill looks legit, I always receive these kinda format of bills from them.

Call up their customer service line and tell them your issue, they should be able to help you with it. Follow their instructions and you should be fine. The previous owner want to pay or not is not your problem, you just let them know when you purchase the property (basically your S&P) and the person they looking for is not you then should be fine edi.

I don't know about SAJ but all my properties in Selangor all have to pay IWK.

No prob. Glad to clarify things up for you.

Btw, do get them to change the name since that you are now the rightful owner. We should pay the IWK bills but only pay for the time when the property is legally yours.

Sometimes the sewage will get stuck and you'll need their help to repair or clear it up. If you don't pay bills later next time got problem.