49 CFR §192.375

1. (a)Each plastic service line outside a building must be installed below ground level, except that—
   1. (1)It may be installed in accordance with § 192.321(g); and
   2. (2)It may terminate above ground level and outside the building, if—
      1. (i)The above ground level part of the plastic service line is protected against deterioration and external damage;
      2. (ii)The plastic service line is not used to support external loads; and
      3. (iii)The riser portion of the service line meets the design requirements of § 192.204.
2. (b)Each plastic service line inside a building must be protected against external damage.