How to Retrieve a Specific Pool’s ETH Balance from the PoolManager in Uniswap V4?

[TangMonk]

In Uniswap V2 and V3, you can simply call the pool’s balanceOf function to determine its balance. However, Uniswap V4 centralizes liquidity management through a PoolManager contract that aggregates funds from multiple pools. This design makes it challenging to pinpoint the ETH balance for a single pool.

For example, consider two pools:

	•	Pool A: Contains 1000 TokenA and 1 ETH
	•	Pool B: Contains 1000 TokenB and 1 ETH

Here, the PoolManager holds a combined total of 2 ETH. The key question is: how can we extract the ETH balance corresponding to either Pool A or Pool B using an approach analogous to balanceOf? Although the PoolManager provides a getLiquidity() function, it appears to return a combined value of amount0 and amount1, which does not directly reveal the individual ETH amounts.

Are there any available interfaces or methods that allow us to segregate the liquidity on a per-pool basis? Any insights or suggestions on how to achieve this separation would be greatly appreciated.

[linear]

PROTO-737 How to Retrieve a Specific Pool’s ETH Balance from the PoolManager in Uniswap V4?

[saucepoint]

its not super easy to do onchain -- for a given pool, you need to iterate over each liquidity position (from an offchain indexer) and calculate the underlying token amounts

as an approximation (still wildy inaccurate), you can take a pool's liquidity StateLibrary.getLiquidity and assume that all liquidity is in the full-range. Then you can use LiquidityAmounts to extract the underlying token reserves