Blocked Septic System Plumbing

What Chloelizabeth is talking about (the vent being blocked/bird nest)& many people don't know, is that toilets are vented through the roof of the home. Sometimes, the protective lid or screen comes loose & things can get inside, creating a blockage. Sometimes, if it's been clogged & back-flowed before, it can back up into the vent pipe from the toilet end, creating a blockage there. If the vent pipe gets blocked, the toilet won't flush properly.
That may not be your problem, but it's worth looking into.

You can tell where the vent pipe is by looking at your roof in the area where your bathroom is. If that turns out to be the problem, you can "snake" it or have a plumber do it for you. If you do it yourself, make sure to do an internet search on how to do it properly so you don't make a mess!
Here's just one website talking about it, you can find a lot more if you do a search.

http://wiki.answers.com/Q/Drain_gur ... hen_toilet_is_flushed_or_sink_drains

Hi, thanks for the comments. The pipes are all underground and there isn't an airvent from the toilet, so no possibility of birds nesting. The pipes all run into two processing tanks and these are maintained every 3 months under a service contract. I'm sure a block is developing (as it has happened before), so I'm just after any tricks to use that can dissolve the build up. When it has blocked before we have stuck some hosing down the pipe and unblocked it. That hasn't worked this time, I think it's too far up the pipe. Thanks for any help you can offer.

You have to have them pumped out every so often. Call a septci company. They will come out and empty it into a large truck. Also if your washer has a self cleaning lint filter, that lint is going into your septic tank and not decomposing. Never clean your carpets and put it down the septic tank. Carpit fibers are indistructable. A garbage disposal will not hurt your septic tank. Food is degradable.

I don't think it is the septic system itself, but the air vent from the toilet that is blocked. If the drains are still working, then the septic tank is not full. Birds love to nest in those air vents; I would check that first.

When was the last time that you had your septic tank/tanks pumped out? Septic systems need regular maintenance. We used to have a septic system before we were connected to city sewers.