A stainless steel filter housing is a long term investment, so you want one that is well-built and high performing. Here are some key signs of a premium stainless steel filter housing:

1. Thick and high grade stainless steel – The higher the grade of stainless steel, the more corrosion resistant and durable it is. For most purposes, grade 304 or 316 stainless steel with a thickness of at least 0.5mm is a good choice. Grade 430 stainless steel is more affordable but stains and rusts more easily.
2. Precision welding – A high quality housing will have cleanly welded seams and joints with no uneven surfaces or cracks. The welding process requires high heat, so inferior welding can damage the stainless steel or impair the housing’s strength. Smooth, even welds indicate precision and care.
3. Strong and durable construction – A premium housing is robustly built to withstand high pressures and last many years. It has reinforced frames, brackets and bases. The ports, valves and gauges are strongly fitted. Inferior housings tend to develop leaks or cracks over time with brittle components.
4. Compliance with NSF standards – To be used in potable water treatment, a stainless steel filter housing must meet NSF safety and quality standards. Certified housings have been rigorously tested to verify they do not leach hazardous chemicals or breed bacteria. This ensures the water is safe to drink.
5. High filtration capacity – A quality stainless steel housing provides adequate space for the amount of filter media needed to properly treat the water for the intended use. Small or undersized housings require frequent cartridge replacement and may overflow if circulation is too rapid.
6. Useful features – Some premium housings have useful features like pressure gauges to monitor filter life, automatic shutoff valves, bypass valves for servicing without shutting off water, heater jackets, interior polypropylene or epoxy linings, etc. These added features improve performance, safety and convenience.
7. Strong warranty – A reputable brand that produces high quality stainless steel filter housings will provide a meaningful warranty, often 3-10 years. This demonstrates their confidence in the durability and performance of their products. Look for a brand that also has good customer reviews and service.

In summary, a premium stainless steel filter housing is a worthwhile investment in quality that translates to optimal and long-lasting performance. Compromising on an inferior housing often leads to poor results and higher costs in the long run.