To estimate the FFO (Funds From Operations) / Net Debt ratio for Acea S.p.A. for the year 2022, we need to calculate FFO for 2022 and Net Debt as of the end of 2022 (2023-01-01).

1. **Calculate FFO for 2022**:
FFO is typically defined as Profit/Loss adjusted for depreciation, amortization, impairment losses/reversals, and non-cash interest/income from subsidiaries, plus finance costs paid.
From the data, we have:
- Profit Loss (2022): 311,160,000 EUR
- Adjustments For Depreciation And Amortisation Expense (2022): 594,636,000 EUR
- Adjustments For Impairment Loss Reversal Of Impairment Loss Recognised In Profit Or Loss (2022): 67,680,000 EUR
- Adjustments For Finance Costs (2022): 85,708,000 EUR
FFO = Profit Loss + Depreciation & Amortisation + Impairment Losses + Finance Costs
FFO = 311,160,000 + 594,636,000 + 67,680,000 + 85,708,000 = 1,059,184,000 EUR.

2. **Calculate Net Debt as of the end of 2022**:
Net Debt = Total Financial Debt - Cash and Cash Equivalents.
Financial Debt typically includes non-current and current financial liabilities.
- Other Noncurrent Financial Liabilities (2023-01-01): 4,722,263,000 EUR
- Other Current Financial Liabilities (2023-01-01): 619,418,000 EUR
Total Financial Debt = 4,722,263,000 + 619,418,000 = 5,341,681,000 EUR.
- Cash and Cash Equivalents (Disponibilità Liquide e Mezzi Equivalenti Alla Fine Dell'esercizio Continued Operations, 2023-01-01): 559,908,000 EUR.
Net Debt = 5,341,681,000 - 559,908,000 = 4,781,773,000 EUR.
(Note: This matches the reported "Disponibilità Monetaria Netta" logic, though that specific line item often includes other minor adjustments. Using the standard financial liability lines is the most rigorous approach here).

3. **Calculate the FFO / Net Debt ratio**:
Ratio = FFO / Net Debt
Ratio = 1,059,184,000 / 4,781,773,000 ≈ 0.221497...

Rounding to 4 decimal places, we get 0.2215.

<answer>0.2215</answer>