Q.Is the root system for a eucalyptus a danger to nearby buildings?
We live adjacent to a park, which has several eucalyptus trees. Some neighbors claim the root system is invading their sewer system and growing under driveways and cracking them. Is their root system deep?

90 % of the Eucalyptus tree roots grow in the top 12 inches of soil. This shallow root system grows quickly and the trees tap root most grow down into the soil at least 6 feet to keep the tree upright. The lateral roots spread out up to 100 feet to support the tree. This can be an issue for nearby structures. Eucalyptus trees planted in an urban area can cause problems with damage to sidewalks, foundations, septic systems and water pipes.
A professional should be called if you suspect damage from roots.