If you need to return one _value_ then use `get_var` instead of `get_row`. `get_var` will return a string. `get_row` will return an array or object.

	$spr_liczbe_wodo = $wpdb->get_var ("select liczba_wodo from wp_ow_adres where adres='Street 12/6'");
	var_dump($spr_liczbe_wodo);

The problem with your code, by the way, is that `$spr_liczbe_wodo` is an object, but when you loop over it `$print` is not but you attempt to use it as if it were an object anyway. Through in a couple of `var_dump`s and you can easily see the problem.