Well, i don't really see an issue with this since the condensate water is basically distilled water with neutral PH. The legal issue with it may be due to furnace condensate water which contains carbonic acid. Using a neutralizer will take away almost all the acidity, however some municipalities still don't allow either condensate water to be piped to the sump to account for idiocy.
One possible solution, you can get a condensate pump, and have it pump the water though a tube to any sink, or drain you can run the tube to. The only downside is the sound of the pump turning on ever now and then.
Yes, you can plumb the outlet of the condensate pump into the tailpiece of the shower. Assuming the condensate line is properly trapped, then there should be no problem.
You'll notice in the code snippet below, that it says "If discharged into the drainage system, equipment shall drain by means of an indirect waste pipe.". Which means you cannot, plumb the condensate drain directly into an untrapped waste line or vent.
Uniform Plumbing Code
Chapter 8 Indirect Wastes
814.0 Condensate Wastes and Control.
814.1 Condensate Disposal. Condensate from air
washers, air-cooling coils, fuel-burning condensing
appliances, the overflow from evaporative coolers,
and similar water-supplied equipment or similar air-conditioning
equipment shall be collected and
discharged to an approved plumbing fixture or
disposal area. If discharged into the drainage system,
equipment shall drain by means of an indirect waste
pipe. The waste pipe shall have a slope of not less
than one-eighth (1/8) inch per foot (10.4 mm / m) or 1
percent slope and shall be of approved
corrosion-resistant material not smaller than the
outlet size as required in Table 8-2 for air-cooling
coils or condensing fuel-burning appliances, respectively.
Condensate or wastewater shall not drain
over a public way.
814.3 Point of Discharge. Air-conditioning condensate
waste pipes shall connect indirectly to the
drainage system through an airgap or airbreak to a
properly trapped and vented receptors dry wells,
leach pits, or the tailpiece of plumbing fixtures.
Condensate waste shall not drain over a public
way.
Chapter 2 Definitions
211.0 -I-
Indirect Waste Pipe - A pipe that does not connect
directly with the drainage system but conveys liquid
wastes by discharging into a plumbing fixture, interceptor,
or receptacle that is directly connected to the
drainage system.
222.0 -T-
Tailpiece - The pipe or tubing that connects the
outlet of a plumbing fixture to a trap.
So you could have something like this, with the condensate pump.
If you can maintain the proper slope, you could remove the condensate pump.
In this situation the condensate pump is not required, since the tailpiece of the shower serves as the air gap. And you won't have problems with sewer gas, since the drain is protected by the trap on the shower drain.
You'll want to use proper fittings to connect to the tailpiece, rather than hacking together some leaking contraption. Without knowing the size and material of the condensate drain, I can't tell you exactly what fittings to use. In the end, you should end up with something like this.
You'll cut the tailpiece, and fit in a new 45° wye. Then you'll use whatever adapters and reducers are required, to go from the condensate drain into the PVC wye. The condensate drain has to maintain the minimum slope, so you'll have to work with that as a constraint.
Best Answer
Draining to the sump pit is a common choice.
Another method is to use a small, automatic condensate pump to lift the water up high enough that it can be directed to another drain.