@Override
    public int getNettyWriteBufferLowWaterMark() {
        return clientConfig.getPropertyAsInteger(WRITE_BUFFER_LOW_WATER_MARK, DEFAULT_WRITE_BUFFER_LOW_WATER_MARK);
    }
NOTE that each eventloop has its own connection pool per host, and this is applied per event-loop.
zuul-core/src/main/java/com/netflix/zuul/netty/connectionpool/ConnectionPoolConfigImpl.java