Check each side of the centre consul, could be coming from the air-con evaporator, If the drain is blocked from it, amount of water would depend on the air-con usage. Also, Not sure if yours has one, But my car has a plenum chamber, in front of windscreen, the polen filter goes at the top of it, so it has some access to inside. again if drains get blocked, it will fill up. Mine did, found it just before it flooded the ECM
Sheepdog
March 2011