1.  Send a legal notice to your neighbour whose sanitary line is weak and not well maintained,  to resolve the issue immediately.

2.   If there's no positive response, complain once again to BBMP and also to Police. Police may not take up the matter as it's a civil dispute.

File RTI application with BBMP as to what action has been taken on your complaint 

2)if no action is taken take legal proceedings against neighbour to carry out necessary repairs of his sanitary pipeline 

- Since, you have already filed your complaint before the BBMP , then in case of no positive response you can send the same complaint to the commissioner BBMP or can mail to : [deleted]

- Further, if no action then file an Injunction suit before the Court. 

- Police will not entertain as this is not treated as an offence.

Dear client, you can try talking to your neighbour to resolve this issue amicably. If he is adamant then you can file a case under private nuisance under law of torts. Before that try approaching the municipal authorities to deal with the issue by talking with higher authorities there.

Until and unless the neighbor has intentionally neglected to maintain the sanitary lane passing between both the properties or if he is liable for the damages caused due to this, you cannot hold the neighbor liable for this neither you can take any action against the neighbor if he is not responsible for this sewage seepage.

However since he is the person utilising this sanitary lane for his sewage purpose, you can issue a legal notice to him and also to the local civic body to look into this civil nuisance especially the stench that emanates due to no proper maintenance and also causing damage to your property.

The police will not entertain any complaint in this civil dispute.

You may file a suit for permanent injunction agaisnt the neighbor to direct them to restrain the sewage flow into your property and a mandatory injunction suit agaisnt them to remove the damages and obstacles caused by them in this regard.

If this issue gets resolved by negotiations then great 

If not then you will have to file a suit for mandatory and permanent injunction 

The local body has no role to play 

You can also explore criminal remedy since this amounts to nuisance and annoyance 

But filing a criminal complaint will unnecessarily complicate things and create bitterness with your neighbour 

Now I do understand that the civil suit will take time and it's not a practical solution 

So the only expeditious option is to file a criminal complaint against your neighbor with local police 

You can file complaint to health dept of corporation but if same is damaged due to your work you need to make good the loss