My experience with K19-S (without heater): Product quality: 3/5 Details - My first K19-S unit was delivered DOA; for some reason, the pump did not let water through. The second K19-S unit works well. However, it can sometimes leak after inserting the filled water tank if the external surfaces of the plastic parts are not completely dry. Filter quality: 4/5 Details - I'm satisfied with the water filtering; the filter also reduces TDS from 160-170 to 6-18. Obviously, you can find a "stronger" filter with more stages if needed. Nevertheless, it will be pretty excessive in terms of initial costs, maintenance, and pure-to-drain rate. So, K19-S represents a good balance for a typical big city. It should be more than enough if your water source is not polluted much. Technical Support: 5/5 Details - tech support helped me resolve (essentially, to replace) the first unit. The conversation was easy to go, and there was excellent customer-oriented service. Overall: 4/5