Unless u have well water, get dip test strips. Nitrate/ nitrite cannot be removed by water conditioner. If u have nitrate in water u have to have another water source, only reverse osmosis system can remove it. This comes from fertalizers that could be used near you. If your water has heavy metals it will show up as hard water. They want soft& alkaline water. I don't know if new zeland has water table for u to have a well, but I thaught I'd add that just in case.