Yes, you can use a Fernco coupling underground. Here are the benefits of using such a coupling:
• Easy installation – Can be fitted quickly in minutes with no special tools needed.
• Flexible – Allows for slight expansion and contraction of pipes due to temperature changes.
• Durable – Resists corrosion and wear due to its tough elastomeric material construction.
Overall, it is an ideal solution for connecting two different types of pipes together without sacrificing reliability or safety.