Well from my experience ( wife got very sick one nite and challenged the system)At 1:00 am the system would not pump anymore,I went top side and unscrewed the waste cap.Learned experience (wear gloves)the system had pressurized and vented out the waste cap.Wasnt much ,but very nasty biomaterial.So my 2 cents keep an eye on tank,keep it low if you dont have a lot of capacity or a challenging evening maybe on horizon.