public List<Bill> findBillsByHousehold(Household household)
			throws BillNotFoundException {
		Set<Bill> bills = household.getBills();
		List<Bill> result = new ArrayList<Bill>();
		if (bills.size() == 0) {
			throw new BillNotFoundException(household, "Bill");
		}
		result.addAll(bills);
		Collections.sort(result);

		return result;

	}