No one seems to get this these are foreign made drinking water systems made for low volume use. They are made with cheap carbon filters good for about 400 gallons of DI production water. A 100 GPD membrane has a rejection rate of 90% so if your tap water TDS is 100 the after membrane TDS is 10. The horizontal DI absorbs about 1200 ppm of TDS, This means you'll get 120 gallons of DI water before exhaustion. It isn't about the housings, it's the filters inside that make all the difference. Your better off buying a quality system to start with that has filters that can do the job.
Fahz