40 CFR §142.57

1. (a)A State may require a public water system to use bottled water, point-of-use devices, or point-of-entry devices as a condition of granting an exemption from the requirements of §§ 141.61 (a) and (c), and 141.62 of this chapter.
2. (b)Public water systems using bottled water as a condition of obtaining an exemption from the requirements of §§ 141.61 (a) and (c) and 141.62(b) must meet the requirements in § 142.62(g).
3. (c)Public water systems that use point-of-use or point-of-entry devices as a condition for receiving an exemption must meet the requirements in § 141.62(h).