Dear, client.
answer is 6.
I just read your request carefully and I'm very excited to work on this.
I have rich experience in ARDUINO and MQTT with multi sensors including PSI sensors, flow meters and temp & humidity sensors, which is necessary for your project.
Furthermore, I had developed GPS, GSM and Home seer system and a lot of web applications, this will be useful for your project.
If you want to hire me, we can talk further about the request and start as soon as possible.
I'm looking forward to hearing from you.
Best Regards.
Thank you.