6w solar panel can drive 12v water pump

You could connect a solar panel directly to a water pump. It is not a good idea, though. The erratic pulse of electricity produced by the solar panel will burn out the pump at some point. That process can take a few seconds to a few years. The point is that connecting solar energy directly to a water pump shortens the life of the pump.

Buy a small, low power 12V pump. Connect it straight to the panel. It'll run most of the time when the sun is shining. It probably will work just fine like JRE says. But there could be a slight chance that the panel will over-volt the motor if the motor does not need the whole 10 Watts. @jigneshsorathiya that one won't work, it's for AC power.

The point is that connecting solar energy directly to a water pump shortens the life of the pump. If the pump's design is such that it needs AC voltage, then the pump will burn out quickly. Solar panels produce DC voltage and will burn out AC appliances in a matter of minutes. It gets worse too.

A 12v 10w solar panel will create DC power. You need a DC water pump if you want to run it directly from your solar panel. Also, there is chance your solar panel might create more than 12v power, in which your water pump will get damage in long run.

You need at least one solar panel to operate a single water pump. The reason for this lies in the type of energy solar panels generate, which is direct current (DC), rather than the alternating current (AC) used by most appliances in homes.

Using one of the submersible well pumps that are made to run directly from solar PV panels is a nice solution, but the pumps are expensive and they require quite a bit of PV panel area to drive. So, this would have been an expensive solution for the relatively low flow required.