One thing I quickly learned is that you can't underestimate the value of purified water in this hobby. You don't necessarily need DI (my TDS is 160ppm+ in and 4ppm out on just RO), but it doesn't hurt. You might see if your pro has a TDS meter, and test the commercial water. If the readings are low, you have a relatively small tank, and 5 gallons covers your top off needs and water change needs, than you might be better to stick with your water service. However, if the TDS reading is high, you are getting a lot of algae, or 5 gallons isn't quite meeting your needs you might want to think about an RO or RO/DI unit. Remember to factor in the cost of the disposable filter replacements 1 to 2 times a year depending on (Sediment, 1 or 2 Activated Carbon, and possibly a DI). As for hooking it up, most come with a "garden hose" attachment that fits the threads on most laundry sink faucets. I have a 30 gallon trash can next to the Laundry sink I keep mine in (takes about 12 hours to fill). RO filters come are sold at various gallons per day rates. If you do get one spend a few bucks more to get a larger filter than you think you need. You don't want to wait all day to get 5 gallons, and it can come in handy in a tank emergency.