I'm not a legal expert, but I can offer some general guidance. In a situation where your neighbours have installed a tap that runs from their kitchen into your front garden without your permission, it may be appropriate to take the following steps:
Communication: Start by discussing the issue with your neighbours calmly and politely. Express your concerns about their use of your front garden without your permission. It's possible that they may not be aware of the impact their actions are having on you.
Seeking Council Intervention: If the issue persists and your neighbours continue to use your front garden without permission, you may need to escalate the matter to the local council. Provide them with all the necessary information, including any correspondence, evidence of previous attempts to resolve the issue, and documentation of any damages caused by their actions. The council may intervene and enforce any relevant regulations or restrictions.