I'm new to the forums here but because this is your "bread and butter", I figured I could serve you a helping, hoping that you can serve me some advice.My favorite topic. Yes, I'm an engineer and this poop is my bread and butter.
The frequency of pumping has everything to do with solids accumulation and nothing to do with how much water enters the tank. So taking shorter showers, letting yellow mellow, or using high efficiency clothes washers, toilets, shower heads, or dishwashers has NOTHING to do with pump frequency. The only reason you pump the tank is to remove the solids from the tank before they rise (sludge) or fall (scum) to the tank outlet level and contaminate your drainfield. Sludge is the solid stuff that sinks to the bottom and accumulates into a firm mud. Scum is the white/brown floatable solids like grease and fat that float to the top and create that nice floating layer on top. The clear zone in the middle is the good stuff that will eventually leave the tank to the drainfield after all of the solids either float up or sink down.
The only good thing a premature pump out does for a tank that wasn't needing it is that it gives your drainfield a rest. The rest period is good for a marginal system because if the drainfield is overworked it is saturated with water too often and only anaerobic bacteria can live like that. A drainfield is supposed to be full of aerobic bacteria which need oxygen to quickly eat any remaining nutrients that leave your septic tank. It should take a week or so to refill an empty tank before the first effluent leaves the tank to the rested drainfield.
The above rest is why drainfields are designed with a daily flow rate. The drainfield must remain unsaturated, the ground must accept the effluent faster than your house is dumping it so that the bugs stay aerobic and oxygen levels high. Less flow is always better since it gives you the best chance of staying unsaturated.
So in summary. Only pump your tank when it needs it. 1500 gallons, family of 4, an easy 5 years. Your pumper can tell you how "full" the tank was and whether you could have gone twice as long or maybe three times as long. Better to be conservative and pump early until you establish this history. Still, don't cut it close. Lots of money at risk. The business also has a tool called a "sludge judge" that is a pipe that you insert into the tank to the bottom, put your thumb over the end and lift it out. The layers of sludge, clear, and scum stay separate and you can judge the need for pumping.
Chamber systems are fine if installed properly. The sand backfill is weird. Should be just native soil. The chambers are set onto the ground and since water is supposed to soak into the dry ground below, there is no use for gravel above the chambers. The reason you can reduce the required drainfield area with the chamber systems is that the trench bottom, the soaking area, is not partially blocked by gravel as it would be with a traditional gravel trench system. You've got to grade the trench bottom perfectly level as the chamber systems work by dumping the effluent into the chamber area and using the entire trench bottom for soaking.
Gravel backfill won't hurt though and will prevent an installation error from ruining the system. I suspect the method of failure is that the chambers aren't firmly bedded or sealed into the native soil so the sand easily washes into the chamber area as rainfall/surface water from above falls through the ground and wants to enter the chamber, taking sand with it. Not unlike how a leaky sewer main causes a sinkhole on the surface. Sand is the problem. Either gravel or real soil should be used.
Divert surface water away from the drainfield area.
After living in our new home for 14 years, our system has begun to fail. We have the wet leeching field and when it it pumped, the honey wagon tells is the field leaks back into the tank. The tank has never seen feminine products or food disposals but obviously with three kids, laundry and showers are frequent. We have a family of five and I would need to head back to the town to see exactly what size tank was installed but I know it was sized for 4 bedrooms and 3 bathrooms.
I've seen a few Youtube videos and some discussions surrounding the aerobic pump systems and how they can "save" your septic system. I'm a licensed electrician by trade, very handy with construction and repairs but not very familiar with plumbing and obviously septic systems. Can these conversions work and save us $15k? Are there local or state red tape that I need to be aware of? Can I simply do this on my own?