1. You have to take time off work to meet the plumber ..... time is money
2. You have to call the blocked drain in as an emergency call - costing more
3. A blocked drain can be prevented, why is it blocked at all?
4. Allowing the drain to block is causing major damage to your drainage system
5. What if the drain cannot be cleared?  Excavation & repairs will be required

So how can this be prevented? 

• Stop using the drains – This is by far the cheapest option
• Clear the drain with an Electric Eel or Water Jetter – Band aid Solution, will definitely block again
• Use a chemical treatment such as RootX or Vaporooter – Applied every 12 months, more effective & less damaged caused than drain cleaning
• Trenchless Rehabilitation – A permanent low cost solution, some restrictions apply. 10 year warranty against roots re-occurring
• Excavation & Repair – Depending on the job, If the drain is deep & under a concrete structure or landscaped area this can be expensive.